[gdal-dev] flipping raster in python

[Jamie Adams]

I've written some simple Python code to flip a raster in relation to the
y-axis.  The raster is 20000x19459 and has 4 bands of type Byte, and is
written east to west (I have no idea why).  The script proceeds normally for
the first 2 bands, but slows way down after starting band 3.  I let it run
overnight, and it had processed less than 1000 columnsin band 3, whereas the
previous pace for bands 1&2 was around 1000 columns every 10 seconds.  Here
is the relevant code with a few debugging statements followed by the
gdalinfo output.  The only thing I'm noticing is that the input image is
INTERLEAVED=BAND whereas the output is INTERLEAVED=PIXEL.  Any help is
appreciated.

------------------------------------------------------------------------------
for band in range(1, indataset.RasterCount + 1):
  ## Print the current band
  print 'Band %s' % band

  inband = indataset.GetRasterBand(band)
  outband = outdataset.GetRasterBand(band)

  count = 0
  print count

  for i in range(inband.XSize):

    ## print the current interval of 1k lines
    new_count = int(i / 1000)
    if new_count > count:
      print new_count
      count = new_count

    inline = inband.ReadAsArray(i, 0, 1, inband.YSize)

    outband.WriteArray(inline, inband.XSize - i - 1, 0)

    inline = None

  inband = None
  outband = None

------------------------------------------------------------------------------
Driver: GTiff/GeoTIFF
Files: test.tif
Size is 20000, 19459
Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.257223563,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]
Origin = (-175.536864949200321,33.666235092496755)
Pixel Size = (-0.000062579160220,-0.000054370391310)
Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (-175.5368649,  33.6662351) (175d32'12.71"W, 33d39'58.45"N)
Lower Left  (-175.5368649,  32.6082416) (175d32'12.71"W, 32d36'29.67"N)
Upper Right (-176.7884482,  33.6662351) (176d47'18.41"W, 33d39'58.45"N)
Lower Right (-176.7884482,  32.6082416) (176d47'18.41"W, 32d36'29.67"N)
Center      (-176.1626566,  33.1372384) (176d 9'45.56"W, 33d 8'14.06"N)
Band 1 Block=20000x1 Type=Byte, ColorInterp=Red
  Mask Flags: PER_DATASET ALPHA
Band 2 Block=20000x1 Type=Byte, ColorInterp=Green
  Mask Flags: PER_DATASET ALPHA
Band 3 Block=20000x1 Type=Byte, ColorInterp=Blue
  Mask Flags: PER_DATASET ALPHA
Band 4 Block=20000x1 Type=Byte, ColorInterp=Alpha
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