point_calc {extRatum} | R Documentation |
Point data calculation
Description
Computes three different summary statistics:
(1) TotalArea
total area of each polygon;
(2) NoPoints
number of multipoint objects within a given polygon; and,
(3) Ratio
ratio between NoPoints
and TotalArea
covered within a polygon.
Usage
point_calc(
point_data,
higher_geo_lay,
unique_id_code,
class_col,
crs,
total_points = TRUE
)
Arguments
point_data |
multipoint object of class |
higher_geo_lay |
multipolygon object of class |
unique_id_code |
a string; indicating a unique ID column of |
class_col |
a string; indicating a column name for |
crs |
coordinate reference system: integer with the EPSG code, or character based on proj4string. |
total_points |
logical; if the target is to measure the total number of points set to |
Details
The function requires two sets of data: a layer of geographic polygons, and a layer of points
If points have been categorised into classes, the function can return the same summary
measures for each class if total_points
= FALSE
by specifying the column that contains the classification in class_col
Value
if total_points = TRUE
:
A tibble
data frame objects containing four columns is returned:
the
unique_id_code
ofhigher_geo_lay
the total area of each polygon in
higher_geo_lay
(TotalArea)the total number of point features
point_data
(NoPoints), andthe ratio between the total number of point features
point_data
and the the total area ofhigher_geo_lay
polygon (Ratio).
if total_points = FALSE
:
A list of three tibble
data frame objects is returned.
The object
PointsLong
contains three columns: theunique_id_code
ofhigher_geo_lay
, theclass_col
ofpoint_data
, the number of point featurespoint_data
by class (NoPoints), the total area of each polygon inhigher_geo_lay
(TotalArea) and the ratio between the number of point features by classpoint_data
and the the total area ofhigher_geo_lay
polygon (Ratio).The object
PointsCountWide
: Returns the point counts ofPointsLong
byunique_id_code
andclass_col
in a wide format.The object
PointsRatioWide
: Returns the ratio ofPointsLong
byunique_id_code
andclass_col
in a wide format.
Examples
## Run point_calc() using the packages' dummy data sets.
## The data sets are georeferenced on wgs84. However, a planar system is used to measure areas.
## For the examples provided here, points and polygons relate to the United Kingdom.
## So the British National Grid is used.
## Not run:
## This example returns the total points count and ratio
# outcome1 <- point_calc(
# point_data = points,
# higher_geo_lay = pol_large,
# unique_id_code = "large_pol_",
# crs = "epsg:27700",
# total_points = TRUE)
## This example returns the points count and ratio by class
# outcome2 <- point_calc(
# point_data = points,
# higher_geo_lay = pol_large,
# unique_id_code = "large_pol_",
# class_col = "class_name",
# crs = "epsg:27700",
# total_points = FALSE)
## End(Not run)