In mkoohafkan/arcpy: Interface to 'ArcGIS' 'Python' Modules

The arcpy package provides a small number of helper functions to make working with spatial layer geometries and attributes easier. These helper functions are essentially wrappers for the arpcy Data Access module that support simple transfer of information between spatial layers and R data frames.

To demonstrate the helper functions, we'll set up a workspace with a copy of the California County Boundaries shapefile (available on https://data.ca.gov). A copy of this file is included with the arcpy package.

library(arcpy)

# set workspace
arcpy$env$workspace = tempdir()
arcpy$env$scratchWorkspace = tempdir()

# copy feature for example
fc = arcpy$management$CopyFeatures(system.file("CA_Counties",
  "CA_Counties_TIGER2016.shp", package = "arcpy"), "CA_Counties")

Reading attribute tables is accomplished using the function da_read.

head(da_read(fc, fields = c("FID", "NAME")))

Tokens are also supported by arcpy. If you have the tibble package installed, you can read geometry tokens as list columns.

da_read(fc, fields = c("OID@", "NAME", "SHAPE@TRUECENTROID"))

You can use da_update to modify attributes.

d = da_read(fc, fields = "NAME")
d["NAME"] = paste(d$NAME, "County, CA")
da_update(fc, d)

head(da_read(fc, fields = "NAME"))

You can also use da_update to add additional fields to a table, provided you create the field first.

d = da_read(fc, c("ALAND", "AWATER"))
d["FRACLAND"] = d$ALAND / (d$ALAND + d$AWATER)

arcpy$management$AddField(fc, "FRACLAND", "FLOAT")
da_update(fc, d["FRACLAND"])

You can use da_drop and da_insert to remove and add rows, respectively.

d = da_read(fc)
# extract second row
new.d = d[2,]
# drop second row
da_drop(fc, 2)
# add the row back
da_insert(fc, new.d)

head(da_read(fc))

arcpy$management$Delete(fc)

mkoohafkan/arcpy documentation built on Sept. 4, 2024, 1:50 p.m.