feature_cols.rst

Feature columns

There are special columns representing features. They are declared at dataframe creation time. They are used internaly to make calculations and provide info in computed properties or methods. Feature columns:

• geometry

  declares a geometry. Data types: GeoPoint or GeoSerie

• time

  the date column. Data type: DateTime. Note: this column is created from timestamps

• speed

  the speed column: unit is meters per second. Data type: double

Only the geometry column is required. The others are optional. Example:

dart

final data = <Map<String, dynamic>>[
   <String,dynamic>{
      "geometry": GeoPoint(latitude: 51.0, longitude: 0.0),
      "timestamp": 125855222,
      "speed": 0.0
   },
];
final df = GeoDataFrame.fromRecords(data,
     geometryCol: "geometry",
     speedCol: "speed",
     timestampCol: "timestamp");

featureCols

Get feature columns info:

final fcols = df.featureCols();
final timeCol = df.fcols.timeCol;

Shortcuts to get feature columns info:

final timeCol = df.timeCol;
final geomCol = df.geometryCol;
final speedCol = df.speedCol;
// internal type
print(speedCol.dtype);
// dart type
print(speedCol.type);