utils

Utility functions for working with segmented data.

class pyshepseg.utils.WorkerErrorRecord(exc, workerType)

Hold a record of an exception raised in a remote worker.

pyshepseg.utils.addOverviews(ds)

Add raster overviews to the given file. Mimic rios.calcstats behaviour to decide how many overviews.

Parameters:
dsgdal.Dataset

Open Dataset for the raster file

pyshepseg.utils.deprecationWarning(msg, stacklevel=2)

Print a deprecation warning to stderr. Includes the filename and line number of the call to the function which called this. The stacklevel argument controls how many stack levels above this gives the line number.

Implemented in mimcry of warnings.warn(), which seems very flaky. Sometimes it prints, and sometimes not, unless PYTHONWARNINGS is set (or -W is used). This function at least seems to work consistently.

pyshepseg.utils.estimateStatsFromHisto(bandObj, hist)

As a shortcut to calculating stats with GDAL, use the histogram that we already have from calculating the RAT and calc the stats from that.

pyshepseg.utils.formatTimingRpt(summaryDict)

Format a report on timings, given the output of Timers.makeSummaryDict() Example usage:

tiledSegResult = doTiledShepherdSegmentation(...)
timings = tiledSegResult.timings
summaryDict = timings.makeSummaryDict()
reportStr = formatTimingRpt(summaryDict)
print(reportStr)

Return a single string of the formatted report.

pyshepseg.utils.reportWorkerException(exceptionRecord)

Report the given WorkerExceptionRecord object to stderr

pyshepseg.utils.writeColorTableFromRatColumns(segfile, redColName, greenColName, blueColName)

Use the values in the given columns in the raster attribute table (RAT) to create corresponding color table columns, so that the segmented image will display similarly to same bands of the the original image.

The general idea is that the given columns would be the per-segment mean values of the desired bands (see tiling.calcPerSegmentStatsTiled() to create such columns).

Parameters:
segfilestr or gdal.Dataset

Filename of the completed segmentation image, with RAT columns already written. Can be either the file name string, or an open Dataset object.

redColNamestr

Name of the column in the RAT to use for the red color

greenColNamestr

Name of the column in the RAT to use for the green color

blueColNamestr

Name of the column in the RAT to use for the blue color

pyshepseg.utils.writeRandomColourTable(outBand, nRows)

Attach a randomly-generated colour table to the given segmentation image. Mainly useful so the segmentation boundaries can be viewed, without any regard to the meaning of the segments.

Parameters:
outBandgdal.Band

Open GDAL Band object for the segmentation image

nRowsint

Number of rows in the attribute table, equal to the number of segments + 1.