Terra raster to polygon You signed out in another tab or window. e. The function spatially aggregates the raster to be chopped, the aggregated raster cells are turned into polygons, then each polygon's extent is used to crop the input raster. frame, for each polygon. By default, this extracts the cell info for each polygon of the SpatialPolygonDataFrame. the polygons are buildings (assigned 'value'=1), and the raster is my area of interest. The value(s) in mask that indicate which cells of x should be masked (change their value to updatevalue (default = NA)). frame and st_sfc (but there might be better ways) and you have to convert your terra raster template to a raster package one because fasterize only likes raster objects from the raster package: The problem is that the rasterize() function of the terra package (and similar stars' st_rasterize()) assigns the cell value from the polygon that contains the cell midpoint. negate: logical. I would like to crop a raster based on SpatialPolygons object. The vector support in terra doesn’t change that. When intersecting a SpatExtent and a SpatRaster, the SpatExtent is first aligned to the raster cell boundaries. The raster package has been a central tool for working with geospatial data in R for years. . terra handles large data sets better than raster does. If weights=TRUE or exact=TRUE only mean, sum, min, max and table are accepted). vol. new = ras_temp ras_temp. Stack Overflow. raster(x, maxcell=500000, col) Arguments as. x. I guess if you want to use terra instead of raster, it is because you have speed issues. logical. Setting a new CRS does not change the data itself, it just changes the label. digits: number of digits to round the coordinates to . 10 sf 0. After reading about a solution suggested for the raster package, I tried using terra's focal function with the hi robert. SpatVector: numeric (one value for each (multi-) polygon geometry. There are large areas with missing values NA values, including:. Follow x: SpatRaster, SpatVector or SpatExtent. If x is a SpatRaster, and you are using method="regular" you can specify the size as two numbers (number of rows and columns). You switched accounts on another tab or window. The st_read() function has a parameter for this:. values: typically a numeric vector of length 1 or nrow(x). 14. Hot Network Overview. The values are recycled to nrow(x). Given certain software the cell coordinates represent the lower left of the cell and not the center. If your original data has dimensions that are not a multiple of the resolution you choose, then your cells will not equal the extent of the original raster. That is, distance to or from these cells is not computed (only if grid=FALSE). maskvalues: numeric. Learn R Programming. sf. What it means is that if you work with raster data, you do not need to add an entire package to your workflow, just because you want to create a mask for as. 10 raster 3. 1 km or 5 km) from the boundary of a polygon. mask. 87192 ymin: 11. I also tried to use gdal_polygonize. One of "near", "in", or "out". You can then use lapply on the resulting list object with table to return cell counts of each class. I cannot replicate this issue yet, but here is an example polygon as an rds on Google Drive. Such objects can be used for plotting with the rasterImage function. The number of nodes for each polygon. It plays nicely with the tidyverse packages, and has built-in ggplot2 support. In order to retrieve the highest value of the raster within the area of a polygon, raster::extract can be used. They are represented by a data. See project to *transform* an object from one CRS to another. However, the resulting contours have 10 levels even though I specified the percentage I am interested in from raster. all x: SpatRaster or SpatVector. I ultimately want to take an average of only those raster cells that are within the specified distance from the boundary of shapefile inwards. If x is a SpatVector, this argument is vectorized, meaning that you can provide a different value for each geometry in x; and you can When intersecting a SpatExtent and a SpatRaster, the SpatExtent is first aligned to the raster cell boundaries. – dieghernan. – dbaston. A function can be used to select a subset of the raster cells (by their values). Get the geometry of a SpatVector. select: expression, indicating columns to select. Actually I try to calculate the major pixel values from a raster with a (80,0)) polys <- SpatialPolygonsDataFrame(SpatialPolygons(list(Polygons(list(Polygon(cds1)), 1), Polygons(list(Polygon(cds2)),2))),data. raster: Coerce to a "raster" object; atan2: Two argument arc-tangent; autocor: Spatial autocorrelation; barplot: Bar plot of a SpatRaster; bestMatch: bestMatch; boundaries: Detect boundaries (edges) box: draw a box; boxplot: Box plot of SpatRaster data; buffer: Create a buffer around vector geometries or raster patches 8. The rastertoPolygons function from the raster package doesn't seem to be able to handle this, as I tried running it but gave up after it was going for 7+ hours. 23 million polygons) that I would like to exact raster data to each polygon. r; polygon; raster; crop; # ensure your raster is a terra raster if not already ET_sr_r <- x: character. I have a shapefile (called "shp") containing 177 polygons i. Within this area there are 854 irregularly shaped polygons that I am interested in summary values for (mean and sd), for each of the layers. frame of extents (bounding boxes) that I need to convert to a set of Extracting raster values to a polygon means finding raster cells that intersect with the polygons and get the value of all those cells and assigns them to the polygon. tif to name a few) with various resolutions and coordinate reference systems, it can be challenging to produce accurate maps. Creating raster from shapefile in R. 4 arguments. 3. However, I need the output in the exact same geomet Details. 42731 57. shp, . 68021 54. I want to use this bbox to clip an image which I have as both a raster and a shapefile. 0. kde and raster. new = resample(ras_alti, ras_temp, "bilinear") # set to NA all data in ras_temp corresponding to cells in ras_alti. In this chapter, we provide examples on how to What you are looking for is as. calculate distance of points to polygon boundary using terra package in R. Ok, now to look at handling rasters. shp", package="terra") v <- vect(f) # polygons with polygons or extent e <- ext(5. Is there a way of using just terra::rasterize to accomplish this task? EDIT: As requested in comments, here is a small sample of the input point data to show the format. We will also transform global aridity raster to a polygon using as. raster: Coerce to a "raster" object; atan2: Two argument arc-tangent; autocor: Spatial autocorrelation; barplot: Bar plot of a SpatRaster; bestMatch: bestMatch; boundaries: Detect boundaries (edges) box: draw a box; boxplot: Box plot of SpatRaster data; buffer: Create a buffer around vector geometries or raster patches x: SpatRaster, SpatVector or SpatExtent. inverse: logical. The sf package is the preeminent package for working with vector data in R. The value that masked cells should I have been struggling with this for hours. field: character or numeric. I am doing this using the code from this link: Creating an equal distance spatial grid in R. inverse. R: Aggregating raster to shapefile polygons. Value. [subsetting and [<-replacement methods are defined for raster objects so you can simply do r[ r[] == 1 ] <- NA to get rid of the values where 1 is your nodata value (use NAvalue(r) to find out what R considers your nodata value is supposed to be if you aren't sure). It works for 14 of 16 areas in the shapefile. Examples Run this Extracting raster values to a polygon means finding raster cells that intersect with the polygons and get the value of all those cells and assigns them to the function from the exactextractr package is a faster alternative than terra::extract() for a large raster data as we confirm later (exact_extract() does not work with points data at I have a large multipolygon (5x5km grids) file (1. method: character. SpatRaster: data. If x is a SpatRaster: . Share. That is in attribute table it has 574 rows (i. 4. I did this: cells_score <- terra::extract(temp_rast, shp_muni, exact = T, cells = T, na. nc, . If wkt=FALSE, this is a five-column matrix or data. Details. 5 Extracting and averaging raster values . rm: If TRUE, cells with NA values in all layers are ignored . mask: SpatRaster or SpatVector. inside: logical. I have successfully managed to do this by extracting raster data using the centroid of the polygon: Not sure why but, I have seen this behavior with a few terra functions. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, Here is some code to show the issue: 1 -- reclassify a raster establish a vector of class limits class. Hot Network Questions @Jefferey crop() and mask() only clip the raster according to the rectangular extents of the polygon it does not clip it from within the boundary of the polygon. Check if polygons intersect in R. For vector data, the best way to compute area is to use the longitude/latitude I want to calculate mean, max, and min of raster cells that fall within the municipality including the cells that intersect with the boundary of the polygon. You can only crop entire rows or columns. See crop for the intersection of a SpatRaster with a SpatExtent (or the extent of a SpatRaster or SpatVector) if you want a SpatRaster (not a SpatExtent) as output. Below is my code. The only problem with this is that rasterToPolygon creates a single layer of polygons, and I have no way of individually indexing each one. frame(ID=c(1,2 It computes zonal statistics even faster than terra in some cases. polygons to polygonize. f. raster cells are not smooth. The gdb file contains a column (gridcode) that I need for other calculations within my R script. sf polygons object, or a list of such objects if input has multiple layers. Follow edited May 27, 2021 at 7 What about sf (and stars)?. Here are some general methods for multi-band raster extraction and summary along with benchmarks. polygon? For reference, my current terra version is a bit old, 1. If a raster cell contains multiple polygons, I would rather like to select the value of the polygon (soil-ID), which has the highest aerea cover in a raster cell. For the project I'm working on, the highRes raster is 1x1km global, and the lowRes raster is 25x25km in resolution. Let’s get started and read in the digital elevation model Note that these results will differ from raster::extract because the summation will include the values of all pixels wholly or partially covered by the polygon, whereas raster::extract will include only pixels whose center is covered by the polygon. The value that masked cells should Get or set the coordinate reference system (CRS), also referred to as a "projection", of a SpatRaster or SpatVector. The value should be > 0 if x is a SpatRaster. raster: Coerce to a "raster" object; atan2: Two argument arc-tangent; autocor: everything that is covered by the first polygon is removed from all other polygons, then everything that is covered by ("ex/lux. 16490 50. This is estimated by determining presence/absence of the polygon in at least 100 sub-cells (more of there are very few cells) You can use terra::extract() for extracting raster cell values for polygons as well. This would be something you can download for any part of the world from the web. Commented May 18, 2021 at 8:30 as. True centroids may be outside a polygon, for example when a polygon is "bean shaped", and they are unlikely to I am trying to do a point in polygon analysis This is my polygon my_poly class : SpatVector geometry : polygons dimensions : 2791790, 35 (geometries, attributes) extent : -180, 1 Skip to main Maybe buffer your grid_pts extent and use that to extract your basin roi from poly, then do the terra::extract. 2 Polygons: exact_extract(), terra::extract(), and My current thought process was to convert the raster to a polygon, and then calculate the polygons area and remove the polygons if they weren't large enough. So I get a simple feature (sf) with polygons, I am able to extract in well-known-text (wkt). I am using {raster} to clip (or crop) a raster based on an irregular shapefile (the Amazon biome) but the output always has a rectangular extent. This does not look nice, so I want to display inland NAs in a different colour terra::intersect(ext(my_raster), ext(ne_shp)) But this returns me only the extent that is intersecting. However, this does not seem to work, as it only keeps some of the cells of the raster that are touched by the polygon. Let’s explore using a spatial polygon/shapefile for summarizing a raster (in this case, global SMAP soil moisture) by using extract function from the terra library. See global for "global" statistics (i. If TRUE, non-standard evaluation You can use function raster::extract. If the input raster object was a stack or brick, containing multiple rasters, the list elements are a matrix rather than a vector. If field is a character, it should a variable name in x. If I load this . sub) and have tried using exact_extractr and played around with terra's extract function but can't seem to work out how to go about it. So, it uses the extent of the polygon to crop the raster file, but not the actual shape of the polygon. raster = F) cells_score ID year_value cell fraction 1 14 180741 0. polygons and st_as_sf functions to find the mean soil moisture values for each aridity class. I am extracting the average value for each polygon from the raster layer using terra::extract. Many data enthusiasts Details. However, I don't know to I can do this with the following code, and it works. You can get a polygon from a raster extent by wrapping st_bbox in st_as_sfc. If I zoom into a small section of the image shown below, I can see the edges of the country boundary has jagged image i. By default, raster cells that overlap with target grid cell polygons will be averaged. If x is a SpatVector: a field (variable) name or a vector of the same length as x; or, if x is a SpatVector of polygons, a SpatVector of lines or polygons to split the polygon geometries Arguments x. 5. rm = TRUE, as. raster: Coerce to a "raster" object; atan2: Two argument arc-tangent; autocor: Spatial autocorrelation; barplot: Bar plot of a SpatRaster; bestMatch: bestMatch; boundaries: Detect boundaries (edges) box: draw a box; boxplot: Box plot of SpatRaster data; buffer: Create a buffer around vector geometries or raster patches I have an R function in terra package that takes a raster and polygon and calculates the average of the raster for the polygon. SpatRaster or SpatVector. This may work for the reproducible I'm extracting the area and percent cover of different land use types from a raster based on several thousand polygon boundaries. Use the raster::extract function to extract the raster values to each polygon. NOT TO BE CONFUSED with the Raster* (big R) objects defined by the 'raster' package! Usage ## S4 method for signature 'SpatRaster' as. Summarize Raster Data. 24591428 1 14 180742 In the following example, the extract function tells correctly us that the mean value of r within the polygon x2 is 5. Stack Overflow for Teams Where developers & technologists share private knowledge with coworkers; Advertising & Talent Reach devs & technologists worldwide about your product, service or employer brand; OverflowAI GenAI features for Teams; OverflowAPI Train & fine-tune LLMs; Labs The future of collective knowledge sharing; About the company From a raster you either get the cell centroids or, if a SpatialGridDataFrame object you could plausibly, get the four corner coordinates of each grid cell. I found myself a possible solution following the idea posted here: updating raster values with a vector or matrix of values based on polygon field in R terra. 2) The cells which are overlain by polygons should have a value of 1 and the parts which are not overlain by polygons, should have the value of zero. The following snippet will loop over files and write a GeoPackage with the file name and polygon extent of each raster: and terra::vect() reading in different extents from the same shapefile. The process works fine for limited number of polygons and raster layers, but as I want to scale this up to multiple months with 1000+ polygons, I was wondering if there is a I have the bounding box of a shapefile. In the documentation I found that you can use the argument touches = TRUE to include 'all cells touched by lines or polygons'. shp, I want to make an equal area grid (400 square miles per grid cell) over Wisconsin. 6-30) Description Usage Value. What I want is to change the values in the raster based on which polygon they fall in. We can also use extract() to obtain the values of raster objects of class SpatRaster within polygons of class SpatVector. Polygons: For each of the polygons, identify all the raster cells that intersect with the polygon, and assign a vector of the cell values to the polygon. Next, use st_area to get the crown areas of each. Then, terra:: However, my go to for polygon/raster extraction is still exactextracr::exact_extract because it returns fractional intersection of each pixel (allowing for weighted sum and mean). The raster package can be slow and can However when I try the basic tools like Raster to Polygon I don't have an option to select the color. raster function to create a "raster" (small r) object. However, recently the originators of raster have released the terra package to replace raster. In general, is it possible to convert a terra SpatVectorCollection to a multi-polygon SpatVector so that it can be plotted etc? Specifically, I have a data. In that case, The only problem is that it only accepts polygon as input, but the simplest solution is to create a small buffer around points and summarise values with a function (such as mean or median). 55, 49. polygons(x, round=TRUE, SpatRaster supports handling large raster files that cannot be loaded into memory; local, focal, zonal, and global raster operations; polygon, line and point to raster conversion; integration with modeling methods to make spatial If TRUE and the geometry of x is polygons, the fraction of a cell that is covered by the polygons is returned. The output is a list, so that you can count the number of objects in the list. For each of the polygons, it will identify all the raster cells whose center lies inside the polygon and assign the vector of values of the cells to the polygon. For example, if an input SpatRaster has 100 columns, and fact=12, the output SpatRaster will have 9 columns and the I made this spatraster by cropping an original land cover raster to polygon data (which represent presence of seagrass). If TRUE a multi-point geometry is returned. I repeat this for each raster. You could also take advantage of using terra instead of raster for raster processing. : myraster[cells_id] <- 7 Here is a reproducible example: Note that sf provides the MULTIPOLYGON description while terra describes both POLYGON and MULTIPOLYGON as #> geometry : polygons , so there is not an easy way to tell on terra if you have MULTI or not. 14 – Silviculturalist. In ArcGIS this conversion can be done with the 'raster to Polygon' tool but so far I can't find a way to do the same in R. So far I have tried this: I am trying to create an empty raster layer and I want this empty raster to have the same dimensions, object to terra::rast to create a new empty raster with the same extent. This has nothing to do with improving raster to polygon conversion but, rather a bit of lack of understanding in how this should be applied. Usage ## S4 method for signature 'SpatRaster' as. 00000 55. Also I don't know what my license is but many of the options in my toolbox (like Spatial Analyst) say that I don't have a license for it. We can set the argument weights = TRUE to get, apart from the cell values, the percentage of each cell covered by the > s[371:372,] Simple feature collection with 2 features and 3 fields (with 1 geometry empty) Geometry type: POLYGON Dimension: XY Bounding box: xmin: 76. new below 600 # metre ras_temp. About; terra 1. contour from terra. as. Now I would like to extract all pixel values and their number of occurrences for each polygon. You signed in with another tab or window. numeric. , landcover) to a vector geometry. I found what looks to be an old webpage on terra::gridDistance, from terra v0. Update: I I have a raster which I want to mask using terra::mask(). polygons(patches(my_spat_raster > 1), dissolve = TRUE) and some other variations captured from similar threads, but nothing seems to reproduce it. Although, it is good practice to define a common projection and get all of your data correctly aligned to a standard analysis extend. 177 counties. NAs) in it that I would like to fill, without altering any of the non-NA values. I have an image stored as matrix with grayscale for each pixel. if x is a SpatVector: logical expression indicating the rows to keep (missing values are taken as FALSE) . The workaround is to just use terra::rasterize Always look at your the class of your object class(x)` For terra you need to read the data using terra::rast and not the raster functions eg. frame that must have two or more columns, the first one identifying the (integer) cell library(terra) Then read in a polygon file of administrative boundaries for western Canada. With aggregate you can compute statistics for cell blocks defined by a spatialEco::zonal. g. skiplast: logical. Improve this answer. Description of the methods in the terra package Description. I want to select raster cells that are within a certain distance (for e. , Trouble converting a large raster to polygon using R. I have also tried out exactextractr::exact_extract() but it didn't give me the same values as raster::extract(). 12986 51. Arguments. I've found that the extract function works much faster if I iterate through each individual Compute the area covered by polygons or for all raster cells that are not NA. I want to aggregate raster data to each polygon in a custom shapefile. See Also. I have a raster layer and a polygon layer overlaying the raster. polygons(), which converts each raster cell into a polygon consisting of five coordinates, all of which are stored in memory (explaining Switching from the raster package to terra for spatial analysis by Juliet Cohen Thu, Aug 25, 2022 Spatial data in R has a reputation for being tedious and time consuming. However, I am mostly curious about other approaches to do so (possibly using only raster/terra based methods) whereas the polygon raster does not do that. If TRUE all layers that are not in the subset are selected. A filename; or a "Well Known Text" string; SpatExtent, data. 2. I'm then really wondering why my two output tibbles Nadmin2R from raster extract Geographic distance Description. Skip to main content. subset: if x is a SpatRaster: integer or character to select layers . Spatial data in R has a reputation for being tedious and time consuming. But it can also be important if the coordinate reference system is planar, but not equal-area. Cells with NA are not converted. Note. 5 feet (0. Aggregation starts at the upper-left end of a SpatRaster. new <= 600] = NA # extract the data v2 <- Raster* object . In doing so, it uses the area intersection of each raster cell with the polygon as a weight to do the averaging (for e. But it is incredibly slow with large rasters. 3. Get the geometry (coordinates) of a SpatVector Description. The main difference in multi-band verses single-band is how the data is summarized. ) We use terra::unique to pull the class values from our raster. some grid I now first generate a polygon large enough to encompass the group of points + the buffer, then I crop the raster for each polygon getting a list of raster. promote_to_multi logical; in case of a mix of Point and MultiPoint, or of LineString and MultiLineString, or of Polygon and MultiPolygon, convert all to the Multi variety; defaults to TRUE. tif) tiles at 60cm resolution, downloaded from Google Earth Engine (NAIP 2018 NDVI). geojson, and . As with sf, the terra package has one function -rast()- that can read in just about any raster file format, which it assigns it’s own class SpatRaster. The raster has all values = 1. Implementation of the generic as. polygons, the filling noise with the terra::fillHoles, then converting the polygons to sf object via st_as_sf. Terra::extract delivers unexpected values when extracting table from raster using polygons. On this image I use SLIC algorithm to divide it into areas. This method computes areas for longitude/latitude rasters, as the size of the cells is constant in degrees, but not in square meters. raster: Coerce to a "raster" object; atan2: Two argument arc-tangent; autocor: Spatial autocorrelation; barplot: Bar plot of a SpatRaster; bestMatch: bestMatch; boundaries: Detect boundaries (edges) box: draw a box; boxplot: Box plot of SpatRaster data; buffer: Create a buffer around vector geometries or raster patches I want to do a point in polygon analysis using the terra package. Providing the fun argument to extract is just I have a polygon shapefile and I would like to know how to convert it to a raster, with a new column (variable), like height which is always 1 (constant value). If x is a SpatVector, you can also provide a vector of the same length as x in which case sampling is done separately for each geometry. The clipped raster is written to outfolder with specified format or same format as input raster. If TRUE the points returned are guaranteed to be inside the polygons or on the lines, but they are not the true centroids. updatevalue: numeric. Unit is meter if x has a longitude/latitude CRS, or in the units of the coordinate reference system in other cases (typically also meter). 49516 Geodetic CRS: WGS 84 id class gridcode geometry 371 371 settlements 2 POLYGON EMPTY 372 372 settlements 2 POLYGON ((76. asc") Then I got my I have multiple raster layers (one for each hour; covering contiguous US) and a polygon vector layer. , all of x is considered a single zone), app for local statistics, and extract for an alternative way to summarize values of a SpatRaster with a SpatVector. Is there a straightforward way to convert polygonal SpatVector class objects (from the terra library) to either simple features or SpatialPolygonsDataFrames? Skip to main content. frame with at least two columns ("layer" and "area") and possibly also "value" (if byValue is TRUE), and "zone" (if zones is TRUE). The raster covers the extent of Australia. I have raster layer of days in which the temperature exceeds the threshold of 0 degrees, and a shapefile of the states of United States. How to get . 15. dissolve: logical. Stack Exchange Network. size: numeric. I want to get the mean raster values for each polygon from the rasterlayer within the brick that has the corresponding date (or month in this case) to that polygon. 6-47. Commented May 18, Reading and writing VRTs differ in size and values when using Terra and Stars. I am in a big trouble in converting polygons to raster in R. I have a raster rrepresenting values from 0 to 50 for the world. The below sample data shows it for a single polygon libr Robert, since you are the primary maintainer, what is your opinion on this behavior with as. powered by. 1. See Also Thank you very much, I've added a bit more details to my question. new[ras_alti. NSE: logical. Any idea what commands could clip the raster within the boundary of the given polygon? – I have a raster and a polygon, and I want to make two masks: maximal raster: every cell inside the polygon, including all the cells that the polygon boundary touches; minimal raster: every cell inside the polygon where no cell touches the boundary of the polygon. How to check if raster and polygon are overlapping? 4. If you want to use fasterize then you have to convert your sf polygon to an sf spatial polygon data frame which can be done with a call to st_as_sf and data. I have set of points and I want to extract which polygons do they fall in. I am seeing an issue with some polygon features loading incorrectly as terra SpatVectors. For area of each raster class, you just use a standard conversion of cell area and counts. If y is a numeric value, the cells with that value are ignored. By default, cells extracted within each polygon are cells that have centers covered by the polygon. If you also provide the resolution argument that will address the Randomly sampling polygons from polygon grid using the spatialEco package in R. Use the terra package instead of raster and use as. 14900 69. True centroids may be outside a polygon, for example when a polygon is "bean shaped", and they are unlikely to Is there an equivalent of sp::over() in package terra? To get a data frame showing which geometries of a SpatVector overlay which geometries of another SpatVector -- like this, but using only terra Here another approach using "raster" package. fun: function to select a subset of raster values (only allowed if x has a single layer) n: integer. The documentation of crop, with SpatRaster argument x, and SpatExtent (or the extent of another spatial object) argument y; that argument "snap" is. In this article, we'll delve into the new capabilities of this powerful geospatial analysis tool and what it means for raster package users. (I am running my analysis on pc rather than in Google Earth Engine due to human subjects requirements of my polygon data. limits #[1] 45. From what I've read, exactextractr::exact_extract() accounts for the portion of the cell lying inside the polygon. About; ("ex/lux. With so many different spatial file types (. What I wanted to do is: I have shapefile (i. However, for polygons like x1 what are smaller than the raster, extract returns a value of "NaN" I'm working in R - I have a directory of raster (. 8 spatial 7. This is likely why your polygon is being read in as a multipolygon by default. I have a DEM raster that has small holes (i. Like factors, SpatRaster categories are stored as integers that have an associated label. S. This can be done with terra::as. Results are stored as SpatVector objects. contour_poly <- as. updatevalue. Here, I go cell by cell, converting each cell to a polygon in order to determine which highRes cells are intersected by this polygon. Specifically I want to calculate the fractal dimensions (a user defined function), Morans I (from the raster package), and the mean NDVI value of all the pixels that fall into each polygon. I could able to calculate polygon-wise mean values using the following code: 4. Used to align y to the geometry of x. I am looking for the terra equivalent of raster::gridDistance(, origin = my_origin, omit = my_omit). Objective is to produce a polygon that represents the contour thresholds for the specified value throughout the entire SpatRaster. shp", package="terra") v <- vect(f) # Extract all values within every polygon # ID is the polygon unique number ext <- terra::extract( r I used the terra package for extracting this data. It looks like you're using the sf package. Ignored if y I would like to mask a raster using all the polygons contained in a "SpatialPolygonsDataFrame" object. If the length is below nrow(x) the as. For areal features, you must provide a desired summary metric. Commented Mar 24, 2023 at 19:54. 7) x <- erase I would suggest converting the output from forestTools to a terra::rast object, then using the terra::as. x: SpatVector. How to extract the frequency of raster values from polygons in terra? 1. We will also transform global In terra, multilayer raster data is represented with the SpatRaster class. However, the below example (it is only one case) suggest that spatialEco is less precise. The latest updates to Terra R include Mask Crop functions, which can now follow irregular polygon raster layers. I know that we can use crop function in raster package, raster::crop(rasterFile, SpatialPolygonsObject) but this function is based Raster to polygons conversion. terra provides methods to manipulate geographic (spatial) data in "raster" and "vector" form. If target is a raster grid, then terra::resample is used. For the moment I've simply retained the old raster::rasterize code and convert the output raster to a SpatRaster, but I think I must be missing something obvious. Rdocumentation. The structure of the returned object is a list, containing a data. 1 Reading in data. I am hesitant to update terra because I have a lot of code using terra heavily and the last thing I want to do for this operation is to update and have it all break. The SpatVector class is used to represent vector data such as points, lines and polygons, and their attributes. I tried. But, this code isn't very flexible, and I also need the I have a rather large raster (384 MB) that I am trying to convert to a polygon shapefile in R. I have attempted to use gIntersection and crop (see below). Also, the case of a single polygon whose extracted raster data would not fit into RAM is handled by the max_cells_in_memory argument, which lets you process polygons of any size within a fixed amount of RAM. If TRUE cells that are NA are ignored. I want to calculate class and polygon-wise zonal statistics using terra R package. 2-8 here, but from what I can gather terra::distance is the current replacement for raster::gridDistance (list of terra's replacement functions here). If x has no values, the total area of all cells is returned. 3 Summarizing rasters using shapefles. width: numeric. If TRUE the last point of a polygon (which is the same as the first point) is not included. You can easily do it like this: # first resample the altitude raster to the temperature one so that they are # "aligned" ras_alti. 71864 60. In this module, we will focus on the terra package, which is replacing the raster package for working with raster-based geospatial data. Is there any to smooth them out so that raster cells are not protruding out from the polygon boundary? P. In my examples, in order to obtain just a data frame with no geometric information, I use x: SpatVector or a two-column matrix (point coordinates) y: SpatRaster. 49516 function to summarize the extracted data by line or polygon geometry. x: SpatRaster or SpatVector. And the fast way, may be with Terra . 87235 11. rm: logical. polygons) of 574 species. If a division of the number of columns or rows with factor does not return an integer, the extent of the resulting SpatRaster will be somewhat larger then that of the original SpatRaster. Any help is appreciated. The latter may seem more precise, but that is debatable given that your original data are raster data. I am trying to understand the difference between exact and weights argument in the extract function in terra package. The raster::extract function, when applied to polygons or with the buffer argument, returns a list object where each element in the list contains a vector of the raster values intersecting the polygon. Extract data and look at head of first polygon in returned list. I've been rewriting an R script so it uses terra instead of raster and other packages, and I've managed to do it all except for one painfully simple task - adding an ID column to a SpatVector. How to assign correct projection and extent to a raster using terra r package? Hot Network Questions Is SQL Injection possible if we're using only the IN keyword (no equals = operator) and we handle the single quote I have an empty raster file (r1, Rasterlayer) and I want to calculate for each of the non-NA cells, the euclidian distance to the nearest polygons (S1, SpatialPolygonsDataFrame). Sample data maker: library(terra) maker = function(x,y){rast(matrix(sample(1:18, x*y, TRUE), x, y))} # same scale as Conversion of a SpatRaster, SpatVector or SpatExtent to a SpatVector of polygons. Up until now i tried this: r=raster("myraster. This is probably the most important operation economists run on raster The final type of vectorization involves conversion of rasters to polygons. Then I use extract() in future::future_lapply() extracting the data for the buffer around each point, matching it with the cropped raster. e <- exact_extract(r, p) head(e[[1]]) Here we apply a function, using lapply, to Categorical rasters Description. 15 meters). I read a solution on Unexpected behaviour of extract function in the raster package which suggested rasterizing the polygon, polygonizing the raster, and then using terra::extract. frame: the vector object ID, the IDs for the parts of each object (e. gpkg, . frame with a value for each zone, or a SpatRaster, or SpatVector of polygons. I am trying to convert a raster to geodatabase (gdb) file using R and then read this gdb file back into R. Working with raster data Another important type of spatial file is raster I have a raster stack with 26 layers that represent different weeks of the year. stats uses exactextractr (I have not checked the code, but it told me to install it to be able to use zonal. So you should only set the CRS of a dataset (if it does not come with one) to what it *is*, not to what you would *like it to be*. The sample size. 57393 as. py from GDAL in python via this function by John Baumgartner but after 4. This shapefile is overlaid on a raster. five polygons that together are one spatial object), the x (longitude) and y (latitude) coordinates, and a flag indicating whether the part is a "hole" (only x: SpatRaster or SpatVector. i am trying to use rasterize() to count the number of polygons overlapping individual raster cells (code below). Thank you so much for your detailed answer ! My NDVI raster has a spatial resolution of ~0. A raster has to be made of regularly sized cells. some raster on polygon boundary could be partially intersecting with the polygon). The areas will be in the x/y cars of the input raster. If TRUE, areas on mask that are _not_ the maskvalue are masked. A SpatRaster layer can represent a categorical variable (factor). vol return SpatRaster objects, which I am attempting to convert to polygons via as. All oceans; Large inland regions such as deserts; The problem is that when I plot r all NAs appear with the same colour regardless of whether they are oceans or deserts. You can use fun=table to tabulate raster values for each line or polygon geometry. raster: Coerce to a "raster" object; atan2: Two argument arc-tangent; autocor: Spatial autocorrelation; barplot: Bar plot of a SpatRaster; bestMatch: bestMatch; boundaries: Detect boundaries (edges) box: draw a box; boxplot: Box plot of SpatRaster data; buffer: Create a buffer around vector geometries or raster patches from raster to terra. If y is missing this method computes the distance, for all cells that are NA in SpatRaster x to the nearest cell that is not NA (or other values, see arguments "target" and "exclude"). 4. 6, 6, 49. 87287 ymax: 11. Converting a raster to polygons is intended to convert integer rasters with clustered values (eg. Problem solving overlapping vectors in terra using terra::union. maskvalues. If field is numeric it typically is a single number or a vector of length nrow(x). 9. 49424 xmax: 76. raster (version 3. Reload to refresh your session. Raster data divide space into rectangular grid cells and they are commonly used to represent spatially continuous phenomena, such as elevation or the weather. The categories can be inspected with levels and cats. See comparison here. On-the-fly projection conversion The spTransform (sf) method is used for on-the-fly map projection conversion and datum transformation using PROJ. The extract() function can be used to extract raster values at point locations or obtain summary statistics within polygon or areal features. Only 4, 8, and 16 are allowed . If x is a SpatRaster: a vector of the length nlyr(x). The SpatVector class accounts for single and multi band. raster: Coerce to a "raster" object; atan2: Two argument arc-tangent; autocor: Spatial autocorrelation; barplot: Bar plot of a SpatRaster; bestMatch: bestMatch; boundaries: Detect boundaries (edges) box: draw a box; boxplot: Box plot of SpatRaster data; buffer: Create a buffer around vector geometries or raster patches Switching from the raster package to terra for spatial analysis. It will be notability faster to project the polygons to the same CSR as the raster, defining a new polygon object and then join the tabular results back to the original polygons. rds through readRDS, I have a SpatialPolygonsDataFrame which shows the complete, correct polygon. My ultimate goal is to do a weighted average of raster within a polygon library as. I'm trying to work out how much of the 6 land cover types are present on my spat raster (land. My raster (called "ras") is made of pixels having different pollution values. Your results are what I'd expect. frame (to make a SpatVector of points); a "geom" matrix to make a SpatVector of any supported geometry (see examples and geom); a spatial vector data object defined in the sf or sp packages; or a list with matrices with coordinates. values: logical; include cell values as attributes? multi: logical. 40991 52. I would like to extract the frequency of the pixel values per ecoregion in terra in R. y needs to be aligned to the geometry of x because you cannot crop partial rows or columns. Otherwise, the area of all cells that are not NA is returned. A data. na. It works fine. The thing is that I want to make a new raster as follows: 1) the extents of the new raster should be the same as the old raster. Adding new polygon attribute column based on location withing another polygon in R. I have a raster and vector with the same spatial extent. The thing is accessing the values directly, eg. polygons() from the terra package, the raster package's successor. layer I'm currently having trouble with generating a contour polygon from the data. Your example makes sense to me. stats) which should be more exact if you are considering polygons (the raster package turns them into rasters first, see zonal below). , raster, stack, brick. wbvpwyanuixzcwgmwmomcbvpavobnebbtoogsdatekptllmtxpuxinfx