Statistics

The Statistics operator is a plot operator that computes count statistics over

  • a selection of numerical columns of a single vector dataset, or
  • multiple raster datasets.

The output is a JSON description.

For instance, you want to get an overview of a raster data source. Then, you can use this operator to get basic count statistics.

Vector Data

In the case of vector data, the operator generates one statistic for each of the selected numerical attributes. The operator returns an error if one of the selected attributes is not numeric.

Parameter

ParameterTypeDescriptionExample Value
columnNamesVec<String>The names of the attributes to generate statistics for.["x","y"]
percentilesVec<number>The percentiles to compute for each attribute.[0.25, 0.5, 0.75]

Raster Data

For raster data, the operator generates one statistic for each input raster.

Parameter

ParameterTypeDescriptionExample Value
columnNamesVec<String>Optional: An alias for each input source. The operator will automatically name the rasters Raster-1, Raster-2, ... if this parameter is empty. If aliases are given, the number of aliases must match the number of input rasters. Otherwise an error is returned.["A","B"].
percentilesVec<number>The percentiles to compute for each band.[0.25, 0.5, 0.75]

Inputs

The operator consumes exactly one vector or multiple raster operators.

ParameterType
sourceMultipleRasterOrSingleVectorSource

Errors

The operator returns an error in the following cases.

  • Vector data: The attribute for one of the given columnNames is not numeric.
  • Vector data: The attribute for one of the given columnNames does not exist.
  • Raster data: The length of the columnNames parameter does not match the number of input rasters.

Example JSON

{
  "type": "Statistics",
  "params": {
    "columnNames": ["A"],
    "percentiles": [0.25, 0.5, 0.75]
  },
  "sources": {
    "source": [
      {
        "type": "GdalSource",
        "params": {
          "data": "ndvi"
        }
      }
    ]
  }
}

Example Output

{
  "A": {
    "valueCount": 6,
    "validCount": 6,
    "min": 1.0,
    "max": 6.0,
    "mean": 3.5,
    "stddev": 1.707,
    "percentiles": [
      {
        "percentile": 0.25,
        "value": 2.0
      },
      {
        "percentile": 0.5,
        "value": 3.5
      },
      {
        "percentile": 0.75,
        "value": 5.0
      }
    ]
  }
}