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Working with CSV

Learn how to use CSV files with WKT geometries in GeoETL.

CSV + Geospatial Data​

CSV files store geospatial data by including geometry in WKT (Well-Known Text) format.

WKT Geometry Format​

WKT represents geometries as text strings. Coordinates in WKT are longitude latitude (x y), not latitude longitude.

Creating CSV with Geometries​

Example CSV file with WKT geometries:

name,population,geometry
Tokyo,13960000,"POINT(139.6917 35.6895)"
Delhi,32941000,"POINT(77.2090 28.6139)"
Shanghai,27796000,"POINT(121.4737 31.2304)"

Converting CSV to GeoJSON​

Basic Conversion​

geoetl-cli convert \
  -i cities.csv \
  -o cities.geojson \
  --input-driver CSV \
  --output-driver GeoJSON \
  --geometry-column geometry
IMPORTANT

The --geometry-column parameter is REQUIRED for all CSV operations in GeoETL.

Unlike GeoJSON (which has a standard geometry structure), CSV files can have any column name for geometries. You must explicitly tell GeoETL which column contains your WKT geometries.

If you forget this parameter, you'll get a clear error message with an example.

By default, most CSV files use "geometry" as the column name, but you must explicitly specify it.

Custom Geometry Column​

If your geometry column has a different name:

name,population,wkt
Tokyo,13960000,"POINT(139.6917 35.6895)"
Delhi,32941000,"POINT(77.2090 28.6139)"

Use --geometry-column:

geoetl-cli convert \
  -i cities.csv \
  -o cities.geojson \
  --input-driver CSV \
  --output-driver GeoJSON \
  --geometry-column wkt

Specifying Geometry Type​

For optimization, you can specify the geometry type:

geoetl-cli convert \
  -i points.csv \
  -o points.geojson \
  --input-driver CSV \
  --output-driver GeoJSON \
  --geometry-column wkt \
  --geometry-type Point

Supported types:

  • Point
  • LineString
  • Polygon
  • MultiPoint
  • MultiLineString
  • MultiPolygon
  • Geometry (mixed types - default)

Converting GeoJSON to CSV​

Basic Conversion​

geoetl-cli convert \
  -i cities.geojson \
  -o cities.csv \
  --input-driver GeoJSON \
  --output-driver CSV

This creates a CSV with:

  • All properties as columns
  • Geometry column with WKT strings

Custom Geometry Column Name​

Currently, the geometry column is always named "geometry". In future versions, you'll be able to customize this.

Troubleshooting CSV Issues​

Issue: Invalid WKT​

Error: Failed to parse WKT

Common causes:

# ❌ Missing coordinates
"POINT()"

# ❌ Wrong format
"POINT: -122, 37"

# ❌ Extra spaces
"POINT ( -122  37 )"

Solutions:

# ✅ Correct format
"POINT(-122.4194 37.7749)"

Issue: Geometry Column Not Found​

Error: Geometry column 'geometry' not found

Solution: Specify the correct column name

geoetl-cli convert -i data.csv -o data.geojson \
  --input-driver CSV --output-driver GeoJSON \
  --geometry-column wkt  # or whatever your column is named

Issue: Encoding Problems​

Symptoms: Special characters appear as � or weird symbols

Solution: Ensure UTF-8 encoding

# Convert to UTF-8 (Linux/macOS)
iconv -f ISO-8859-1 -t UTF-8 input.csv > output.csv

# Then convert with GeoETL
geoetl-cli convert -i output.csv -o data.geojson \
  --input-driver CSV --output-driver GeoJSON

Issue: Empty Output​

Symptoms: Conversion succeeds but output is empty

Possible causes:

  1. Input CSV is empty
  2. No geometry column found
  3. All WKT strings are invalid

Debug with verbose mode:

geoetl-cli -v convert -i data.csv -o data.geojson \
  --input-driver CSV --output-driver GeoJSON \
  --geometry-column geometry

Large CSV Files​

For large files, use verbose mode to monitor progress:

geoetl-cli -v convert -i large_data.csv -o large_data.geojson \
  --input-driver CSV --output-driver GeoJSON \
  --geometry-column geometry

Quick Reference​

# Basic CSV to GeoJSON (--geometry-column REQUIRED for CSV)
geoetl-cli convert -i data.csv -o data.geojson \
  --input-driver CSV --output-driver GeoJSON \
  --geometry-column geometry

# Custom geometry column name
geoetl-cli convert -i data.csv -o data.geojson \
  --input-driver CSV --output-driver GeoJSON \
  --geometry-column wkt

# Specify geometry type for optimization
geoetl-cli convert -i data.csv -o data.geojson \
  --input-driver CSV --output-driver GeoJSON \
  --geometry-column wkt \
  --geometry-type Point

# GeoJSON to CSV (no geometry-column needed for GeoJSON input)
geoetl-cli convert -i data.geojson -o data.csv \
  --input-driver GeoJSON --output-driver CSV

# Verbose output
geoetl-cli -v convert -i data.csv -o data.geojson \
  --input-driver CSV --output-driver GeoJSON \
  --geometry-column geometry

References​

See Also​