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Adding an ID and applying a buffer

This step aims at preprocessing a vector file containing observation points or polygons. It adds an ID column if one does not already exist, and can also apply a buffer to erode or dilate observations.

It is optional if one uses a dataset which already contains an ID column and does not which to apply a buffer to it.


The input parameters are:

  • obs_path : Path of vector file containing observation points or polygons to preprocess
  • export_path : Path used to export the resulting preprocessed observation points or polygons
  • buffer (optional) : Length in meters of the buffer used to dilate (positive integer) or erode (negative integer) the observations. If None, no buffer is applied. Some observations may disappear completely if a negative buffer is applied.
  • name_column (optional) : Name of the column used to identify observations. If the column doesn't already exists, it is added as an integer between 1 and the number of observations. The default is "id".


The output is a vector file at export_path derived from the vector file at obs_path, with up to two modifications :

  • An ID attribute named after the name_column parameter is added, if not already present.
  • A buffer can be applied, positive or negative

How to use

From a script

from fordead.validation.preprocess_obs import preprocess_obs

preprocess_obs(obs_path = <obs_path>, export_path = <export_path>, name_column = <name_column>, buffer = <buffer>)

From the command line

fordead preprocess_obs [OPTIONS]

See detailed documentation on the site

How it works

Importing the vector file containing observations

The vector file at obs_path is imported using the geopandas package.

Adding an ID column to the vector

If name_column does not exist in the vector file, each observation is attributed an ID from 1 to the length of the GeoDataFrame object.

Functions used: attribute_id_to_obs()

Applying a buffer

If the buffer parameter is used, a buffer is applied on the observations to erode if buffer is negative, or to dilate if it is positive.

Functions used: buffer_obs()

Exporting the resulting the vector file

The modified GeoDataFrame object is exported to export_path.