Contents
How are simple features represented in a SF object?
Manipulating Simple Features This vignette describes how simple features, i.e. records that come with a geometry, can be manipulated, for the case where these manipulations involve geometries. Manipulations include: Features are represented by records in an sf object, and have feature attributes (all non-geometry fields) and feature geometry.
Can you write to a geodatabase via SF?
Second, you can’t write to geodatabases via sf; you can only read them. You have a couple of options. You can save your data as a shapefile (or any other spatial data format) outside of the geodatabase with sf:
How to import spatial data files in SF?
The short report printed gives the file name, mentions that there are 77 features (records, represented as rows) and 10 fields (attributes, represented as columns), states that the spatial data file is a MULTIPOLYGON, provides the bounding box coordinates, and identifies the projection method (which we will discuss later).
How does the package SF read and write?
Package sf reads and writes using GDAL by the functions st_read and st_write. The data model GDAL uses needs a data source, which may be a file, directory, or database a layer, which is a single geospatial dataset inside a file or directory or e.g. a table in a database.
How to create spatial polygons from a Dataframe?
I have a dataframe containing the coordinates of a set of polygons. This is how I would convert it to a spatialPolygons (package sp)
Can a SF object have more than one geometry column?
The special geometry column is itself a list of class sfc, which is made up of individual objects of class sfg. While it is possible to have multiple geometry columns, sf objects usually only possess a single geometry column. We can break down the components of an sf object by looking at its printed output.
When to use empty geometry instead of SF?
In case of no matching geometry, an empty geometry is substituted. The second argument should be a data.frame (or similar), not an sf object: For joining based on spatial intersections (of any kind), st_join is used: The join method is a left join, retaining all records of the first attribute:
How do you join an object in SF?
We can do this by The usual join verbs base R ( merge) and of dplyr ( left_join, etc) work for sf objects as well; the joining takes place on attributes (ignoring geometries). In case of no matching geometry, an empty geometry is substituted.
Which is an example of a simple feature geometry?
Low-level examples are: Just to make the point, we can for instance rotate the counties of North Carolina 90 degrees clockwise around their centroid, and shrink them to 75% of their original size: The coordinate reference system of objects of class sf or sfc is obtained by st_crs, and replaced by st_crs<-:
Can a spatial data file be stored in R?
R has well-supported classes for storing spatial data ( sp) and interfacing to the above mentioned environments ( rgdal, rgeos ), but has so far lacked a complete implementation of simple features, making conversions at times convoluted, inefficient or incomplete. The sf package tries to fill this gap.
How are m-coordinates similar to SF data structures?
Similarly, M-coordinates need an attribute reference system, e.g. a measurement unit. sf stores simple features as basic R data structures (lists, matrix, vectors, etc.). The typical data structure stores geometric and feature attributes as a data frame with one row per feature.