I have a large point vector file (and many others like it), where each point has a integer value in the column "DN". However, I only need 6 points per DN and want them to be selected randomly. As a final output, I need one csv that contains 6 points per DN value.
Thus far, I have been able to successfully print out the number of points in each DN value, and generate a list of 6 random numbers that I want to use for selecting each grouping of DN value points:
import geopandas as gpd import random # Importing point file point_df = gpd.read_file('/home/file_path/file.geojson') # List of known target DN values within my point file dn_values_list = [0, 3, 6, 8, 11, 14, 17, 19, 22, 25, 28, 31, 33, 36, 39, 42, 44, 47, 50, 53, 56, 58, 61, 64, 67, 69, 72, 75, 78, 81, 83, 86, 89, 92, 94, 97] for dn_value in dn_values_list: # Filtering point file by DN value filtered_point_df = point_df[point_df['DN'].isin([dn_value])] print(str(dn_value) + " DN:", str(len(filtered_point_df)) + " points") # Generating random list of 6 row numbers to use for each DN value random_list = random.sample(range(1, (len(filtered_point_df))), 6) random_list.sort() print(dn_value, random_list)
However, things have gotten a bit trickier now that I am trying to select and export the 6 rows from each DN value to put into a CSV. I technically need two filters: the first one being on the DN value (achieved already!) and the second being the position decided within the random number list (still need help with). I've tried it with a nested for loop but am running into errors:
for random_integer in random_list: selected_point_gdf = filtered_point_df[random_integer] selected_point_gdf.to_csv('test.csv', index=False)
How do I select the random 6 rows for each DN value, add it to a GDF, and export to csv with lat/long or geojson?