Validate KML geometries in python

data validationgeometrykmlpython

I have a CSV file where in a column there are some KML geometries.
These geometries can be points, lines, polygons etc. I would like to validate them and check if they are correctly written.

I'm reading the CSV with Pandas

import pandas as pd
csv = read_csv('file.csv')

#Let's take into account just the first location
coordinates = csv.['location'].loc[0]

coordinates would be:

<Point><coordinates>2.34880,48.85341</coordinates></Point>

I tried to proceed with fastKML, but it searches for a complete KML file to check and not just the string I got.

So I'm wondering, is there any possibility to validate directly the sting?

Edit: With the tip from @user2856 I manage to check the geometry.

i.e.:

kml_start="<kml xmlns='http://www.opengis.net/kml/2.2'><Placemark><name>Simple placemark</name><description>Test.</description>'"
kml_end = "</Placemark></kml>"
kml_test = kml_start+str(coordinates)+kml_end

try:
    k = kml.KML()
    k.from_string(kml_test)
    print("geometry")
except:
    errors +=1
    print("Error, no Geometry")

Best Answer

Perhaps wrap it into a complete KML string for a simple placemark, then parse it with fastkml from_string:

e.g.

import pandas as pd
csv = read_csv('file.csv')

#Let's take into account just the first location
coordinates = csv.['location'].loc[0] 

kml_template = """
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
  <Placemark>
    <name></name>
    <description></description>
    {}
  </Placemark>
</kml>
"""

k = kml.KML()
k.from_string(kml_template.format(coordinates))

Related Solutions

[GIS] Reading geopackage geometries in Python

You can use the gdal/ogr, fiona (built on gdal/ogr) or geopandas (built on fiona) python libraries.

Below is a fiona example:

import fiona

# No need to pass "layer='etc'" if there's only one layer
with fiona.open('test.gpkg', layer='layer_of_interest') as layer:
    for feature in layer:
        print(feature['geometry'])

Partial output for one record in my data:

{'type': 'MultiPolygon', 'coordinates': [[[(147.01294051, -34.75046834699997), (147.01289292100003, -34.75075388199998), (147.01251220799998, -34.75068249799993), etc...

From the fiona docs:

A record you get from a collection is a Python dict structured exactly like a GeoJSON Feature. Fiona records are self-describing; the names of its fields are contained within the data structure and the values in the fields are typed properly for the type of record. Numeric field values are instances of type int and float, for example, not strings.

[GIS] Combine KML files with Python

You can use the fastkml python lib for this. It can be found at https://fastkml.readthedocs.io/en/latest/ with all instructions to the usage.

Here is a code example for using this library to generate a kml structure.


from pathlib import Path

from fastkml import kml
from shapely.geometry import shape


def read_kml(kml_text):
    k = kml.KML()

    # Reading the kml from a text string
    k.from_string(kml_text)

    k_doc = list(k.features())[0]

    # Getting the first document child that must be a folder or a placemark
    # but you can iterate over it to get multiple folders or placemarks
    doc_child = list(k_doc.features())[0]

    lst_geoms = list()
    if isinstance(doc_child, kml.Folder):
        for feature in doc_child.features():
            lst_geoms.append(feature.geometry)
    elif isinstance(doc_child, kml.Placemark):
        lst_geoms.append(doc_child.geometry)

    # Returning the geometries found list  
    return lst_geoms


def generate_kml():
    # Final file IO
    k = kml.KML()
    ns = '{http://www.opengis.net/kml/2.2}'

    # Creating document structure
    document = kml.Document(
        ns, "SOME_IDENTIFICATION",
        "SOME_NAME", "SOME_DESCRIPTION"
    )
    k.append(document)

    # Creating folder structure
    # Note that a kml can have multiple folders
    folder = kml.Folder(
        ns, "SOME_IDENTIFICATION",
        "SOME_NAME", "SOME_DESCRIPTION"
    )
    document.append(folder)

    # Creating placemark structure
    # Note that a kml can have multiple placemarks
    placemark = kml.Placemark(
        ns, "SOME_IDENTIFICATION",
        "SOME_NAME", "SOME_DESCRIPTION"
    )
    # Passing the geometry to the placemark
    # It can be a shapely geom (Polygon, MultiPolygon, Polyline, Point, etc)
    placemark.geometry = shape("SOME_GEOJSON_GEOMETRY_HERE")

    # Adding the placemark to the previous created folder
    folder.append(placemark)

    final_kml_text = k.to_string(prettyprint=True)

    output = Path(__file__).parent / "test.kml"
    output.write_text(final_kml_text.encode("UTF-8"))


if __name__ == '__main__':
    # U can either generate a kml from a existing data
    generate_kml()
    # or read another kml to get the features and properties
    # to generate your own
    geometries = read_kml("SOME_KML_STRINGIFIED_TEXT")

Best Answer

Related Solutions

[GIS] Reading geopackage geometries in Python

[GIS] Combine KML files with Python

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