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How to save spatialpolygons as a shapefile in R?
We can save our SpatialPolygons object as a shapefile using the raster package. The shapefile function in the raster package is very convenient in that it can both read a shapefile into R but it can also write a SpatialPolygons or other spatial object classes (lines, polygons, etc.) to a shapefile.
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 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.
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.
Can you dissolve state boundaries into one polygon?
We can get around that by dissolving boundaries based on similar attributes. Essentially collapsing multiple polygons into a single polygon. Here we’re going to dissolve the state boundaries to make a single United States (lower 48) border polygon.
What is the syntax for a polygon function in R?
Basic R Syntax: polygon (x_coordinates, y_coordinates) The R polygon function draws a polygon to a plot. The basic R syntax for the polygon command is illustrated above.
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: