Plot allocation

Allows the allocation of sampling plots with various types of sampling and plot formats. If you prefer a visual interface, consider using the QGIS module.

Class Parameters

PlotAllocation(shp_dir, epsg)

Parameters	Description
shp_dir	Directory of the shapefile defining the boundary of the area to be sampled.
epsg	The EPSG code of the shapefile defining the boundary of the area to be sampled.

Class Methods

methods and parameters

PlotAllocation.create_plots(distribution, plot_format, plot_area, sample_number,
                            by_hectare, min_border_distance, rectangle_size,
                            x_y_angle, save_buffer, show_plot, save_dir)

Parameter	Description
distribution	Type of distribution or allocation that the plots should be subjected to.
plot_format	Format of the plot that will be installed.
plot_area	Area of the plot that will be installed. Not used when plot_format = 'rectangle'
sample_number	Could be the number of plots, the percentage of the total area that will be sampled or a column in the attribute table containing the number of plots per polygon. If value < 1 it will be understood as a percentage. If value >= 1 it will be understood that you are setting the quantity of plots to allocate.
by_hectare	If True, will use sample_number as plots per hectare. If sample_number < 1, it will use the percentage only.
min_border_distance	Minimum distance in meters that the plots must be from the edge of the shapefile boundaries.
rectangle_size	Used when plot_format = 'rectangle'. Tuple containing the sizes of X and Y of the rectangle (x,y).
x_y_angle	Used when distribution = 'systematic custom'. Sets the distance in X and Y of each line in the grid of the systematic distribution and also the rotation angle in degrees (x,y,angle).
save_buffer	If true, saves the buffer considering the plot size around the point.
show_plot	If true, displays a figure of the allocation performed.
save_dir	Directory where the shapefiles will be saved. If None, no shapefile will be saved.

Available arguments

Type of distributionPlot formatEPSG

random : Allocate the plots in a random distribution
best sampling : (recommended) Allocate the plots in the best possible distribution for the area considering the established parameters.
systematic : Allocate the plots in a grid distribution, does not allow the definition of sample_number and alocate all possible plots.
systematic custom : Allocate the plots in a grid distribution with the x and y distances from the grid lines and grid rotation angle defined by the user.

round : Consider that plots will have a rounded shape.
squared : Consider that plots will have a squared shape.
rectangle : Allows user to insert the X and Y sizes of the desired rectangle shape.

In order to achieve the best precision in calculation, you must select the UTM zone that your area is in. Find your utm zone.

Example Usage

Consider the data from 3 fictitious forest stands, located in a forest near the Federal University of Santa Maria, Frederico Westphalen Campus, Brazil.
Download example shapefile.

Attribute table information:

id	talhao	area_ha	n_par
1	A	4.049	3
2	B	15.521	5
3	C	39.964	14

Random distribution

plot_allocation_example_1.py
from fptools.inventory_plots import PlotAllocation#(1)!

plots = PlotAllocation(r"your/path/exemplo_shapefile.shp", epsg='32722')#(2)!

plots.create_plots(distribution="random", sample_number="n_par",
                   plot_area=400, min_border_distance=2, 
                   save_dir="C:/Users/Desktop",
                   show_plot=True, save_buffer=True)#(3)!

Import PlotAllocation class.
Create the plots variable with PlotAllocation class. Defines the boundary area shapefile path and the epsg.
Create the plots with random distribuition, using "n_par" column on the atributte table to define the number of plots, plot area = 400 m², a minimum border distance of 2 meters and save the shapefile in C:\Users\Desktop.

example-1 — As `show_plot=True`, a preview figure showing the plot allocation will be generated.

Systematic custom distribution

plot_allocation_example_2.py
from fptools.inventory_plots import PlotAllocation#(1)!

plots = PlotAllocation(r"your/path/exemplo_shapefile.shp", epsg='32722')#(2)!

plots.create_plots(distribution="systematic custom", x_y_angle=(100,50,45),
                    plot_area=400, min_border_distance=2, save_dir="C:\Users\Desktop",
                    show_plot=True, save_buffer=True)#(3)!

Import PlotAllocation class.
Create the plots variable with PlotAllocation class. Defines the boundary area shapefile path and the epsg.
Create the plots with systematic custom distribuition, plot area = 400 m², with x distance = 100 meters, y distance = 50 meters and 45° of grid rotation, with a minimum border distance of 2 meters and save the shapefile in C:\Users\Desktop.

example-2 — As `show_plot=True`, a preview figure showing the plot allocation will be generated.

Rectangle plot format

plot_allocation_example_3.py
from fptools.inventory_plots import PlotAllocation #(1)!

plots = PlotAllocation(r"your/path/exemplo_shapefile.shp", epsg='32722')#(2)!

plots.create_plots(distribution="best sampling", rectangle_size=(20,30),
                    sample_number = 2, by_hectare = True,
                    min_border_distance=2, save_dir="C:\Users\Desktop",
                    show_plot=True, save_buffer=True)#(3)!

Import PlotAllocation class.
Create the plots variable with PlotAllocation class. Defines the boundary area shapefile path and the epsg.
Create the plots with best sampling distribuition, a rectangle width (x) = 20 meters and height (y) = 30 meters, a sampling of 2 plots per hectare, with a minimum border distance of 2 meters and save the shapefile in C:\Users\Desktop.