Contents
- 1 How to create a spatial polygon in R?
- 2 What’s the difference between spatial and spatialpolygonsdataframe?
- 3 How are polygons determined in spatial data manipulation?
- 4 How to change the projection of shapefile-Stack Overflow?
- 5 How to intersect lines and polygons in R?
- 6 How to combine polygons and points in R-stack?
- 7 Which is the function of the spatialpolygons function?
- 8 How are spatialpolygons objects created by reading from rgdal?
- 9 What are the vertices of a spatial polygon?
How to create a spatial polygon in R?
Most people deal with SpatialPolygon files that have already been created and are read into R via a shapefile. In the next portion of this tutorial we’ll download a SpatialPolygonDataFrame that contains US State boundaries. We can get the data directly from within R using the getData function available in the raster package.
What’s the difference between spatial and spatialpolygonsdataframe?
The difference between SpatialPolygons and SpatialPolygonsDataFrame are the attributes that are associated with the polygons. SpatialPolygonsDataFrames have additional information associated with the polygon (e.g., site, year, individual, etc.) while SpatialPolygons contain only the spatial information (vertices) about the polygon.
How are polygons determined in spatial data manipulation?
In order to determine the polygons we use st_intersects, a geometric binary which returns a vector of logical values, which we we can use for subsetting. Note the difference to st_intersection, which performs a geometric operation and creates a new sf object which cuts out the area of the buffer from the polygons a like cookie cutter.
How to use spatial data manipulation in R?
If you don’t have the object still loaded read the the PhillyTotalPopHHincshapefile into an object named philly_sf. Check out the column names of philly_sfand of ph_eduto determine which one might contain the unique identifier for the join. ## sf ## # if you need to read in again:# philly_sf <- st_read(“data/Philly/”)names(philly_sf)
How to transform a SP object in R?
I spent a few months doing spatial stats stuff in R, but it was 5 years ago. For the life of me, I cannot remember how to transform an sp object (e.g. SpatialPolygonsDataFrame) from one projection to another.
How to change the projection of shapefile-Stack Overflow?
I am trying to change or assign the projection of a Germany-Shapefile from NA to +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0, but somehow it doesn’t work well. Reproducible Example: Shapefile and other files can be downloaded here:
How to intersect lines and polygons in R?
Following on from an answer about intersecting polygons with lines to chop up a polygon into smaller polygon units (in QGIS), I wanted to try the same thing in R. However, I cannot seem to find a method that works!
How to combine polygons and points in R-stack?
If you do overlay (pts, polys) where pts is a SpatialPointsDataFrame object and polys is a SpatialPolygonsDataFrame object then you get back a vector the same length as the points giving the row of the polygons data frame. So all you then need to do to combine the polygon data onto the points data frame is: HOWEVER!
How to extract height from a raster in R?
When we use the extract () function with fun=max, R returns a dataframe containing the max height calculated from all pixels in the buffer for each plot. There are a few other popular packages that have a function called extract (), so we will specify to use the function from the raster package using the ” :: ” notation.
How to create a spatial polygon layer from scratch?
Let’s begin by creating a set spatial polygons layer from scratch. We’ll use the sp package to make a SpatialPolygons object. First we need to create a set of XY coordinates that represent the vertices of a polygon. We’ll use use some randomly generated XY coordinates.
Which is the function of the spatialpolygons function?
Polygon returns an object of class Polygon ; Polygons returns an object of class Polygons ; SpatialPolygons returns object of class SpatialPolygons ; SpatialPolygonsDataFrame returns object of class SpatialPolygonsDataFrame getSpatialPolygonsLabelPoints returns an object of class SpatialPoints with label points.
How are spatialpolygons objects created by reading from rgdal?
SpatialPolygons objects created by reading using readOGR from rgdal have the comments set on input, as OGR also uses SFS. Refer to Bivand et al. (2013), pages 47-48 and 132-133 for a further discussion. Roger Bivand, Edzer Pebesma and Virgilio Gomez-Rubio, 2013.
What are the vertices of a spatial polygon?
Spatial polygons are a set of spatially explicit shapes/polygons that represent a geographic location. Spatial polygons are composed of vertices which are a set of a series of x and y coordinates or Spatial points. Spatial polygons can be combined with data frames to create what’s called a SpatialPolygonsDataFrame.
How are spatiallinesdataframe and spatialpolygonsdataframeobjects defined in R?
SpatialLinesDataFrameand SpatialPolygonsDataFrameobjects are defined using SpatialLinesand SpatialPolygonsobjects and data frames. The ID fields are here required to match the data frame row names.
How to convert a spatialpolygon to a polygon?
When the Error: “row.names of data and Polygons IDs do not match” arise this solution seems to be helpful: rename IDs of the dataframe to match IDs of the polygons: I find the following solution generally works. Then use df as the second argument to the spatial dataframe conversion function: