lib.iolib module

Functions for IO, mostly wrapped around GDAL

Note: This was all written before RasterIO existed, which might be a better choice.

pygeotools.lib.iolib.b_getma(b)

Get masked array from input GDAL Band

Parameters:b (gdal.Band) – Input GDAL Band Returns:Masked array containing raster values Return type:np.ma.array

pygeotools.lib.iolib.cpu_count(logical=True)

Return system CPU count

pygeotools.lib.iolib.ds_getma(ds, bnum=1)

Get masked array from input GDAL Dataset

Parameters:

• ds (gdal.Dataset) – Input GDAL Datset
• bnum (int, optional) – Band number

Returns:

Masked array containing raster values

Return type:

np.ma.array

pygeotools.lib.iolib.ds_getma_sub(src_ds, bnum=1, scale=None, maxdim=1024.0, return_ds=False)

Load a subsampled array, rather than full resolution

This is useful when working with large rasters

Uses buf_xsize and buf_ysize options from GDAL ReadAsArray method.

Parameters:

• ds (gdal.Dataset) – Input GDAL Datset
• bnum (int, optional) – Band number
• scale (int, optional) – Scaling factor
• maxdim (int, optional) – Maximum dimension along either axis, in pixels

Returns:

Masked array containing raster values

Return type:

np.ma.array

pygeotools.lib.iolib.fn_check(fn)

Wrapper to check for file existence

Parameters:fn (str) – Input filename string. Returns:True if file exists, False otherwise. Return type:bool

pygeotools.lib.iolib.fn_check_full(fn)

Check for file existence

Avoids race condition, but slower than os.path.exists.

Parameters:fn (str) – Input filename string. Returns:True if file exists, False otherwise. Return type:status

pygeotools.lib.iolib.fn_getds(fn)

Wrapper around gdal.Open()

pygeotools.lib.iolib.fn_getma(fn, bnum=1, return_ds=False)

Get masked array from input filename

Parameters:

• fn (str) – Input filename string
• bnum (int, optional) – Band number

Returns:

Masked array containing raster values

Return type:

np.ma.array

pygeotools.lib.iolib.fn_getma_sub(fn, bnum=1, scale=None, maxdim=1024.0, return_ds=False)

pygeotools.lib.iolib.fn_list_check(fn_list)

pygeotools.lib.iolib.fn_list_valid(fn_list)

pygeotools.lib.iolib.gdal2np_dtype(b)

Get NumPy datatype that corresponds with GDAL RasterBand datatype Input can be filename, GDAL Dataset, GDAL RasterBand, or GDAL integer dtype

pygeotools.lib.iolib.get_auth()

Get authorization token for https

pygeotools.lib.iolib.get_datadir()

pygeotools.lib.iolib.get_ndv_b(b)

Get NoData value for GDAL band.

If NoDataValue is not set in the band, extract upper left and lower right pixel values. Otherwise assume NoDataValue is 0.

Parameters:b (GDALRasterBand object) – This is the input band. Returns:b_ndv – NoData value Return type:float

pygeotools.lib.iolib.get_ndv_ds(ds, bnum=1)

pygeotools.lib.iolib.get_ndv_fn(fn)

pygeotools.lib.iolib.get_sub_dim(src_ds, scale=None, maxdim=1024)

Compute dimensions of subsampled dataset

Parameters:

• ds (gdal.Dataset) – Input GDAL Datset
• scale (int, optional) – Scaling factor
• maxdim (int, optional) – Maximum dimension along either axis, in pixels

Returns:

• ns – Numper of samples in subsampled output
• nl – Numper of lines in subsampled output
• scale – Final scaling factor

pygeotools.lib.iolib.getfile(url, outdir=None)

Function to fetch files using urllib

Works with ftp

pygeotools.lib.iolib.getfile2(url, auth=None, outdir=None)

Function to fetch files using requests

Works with https authentication

pygeotools.lib.iolib.image_check(fn)

pygeotools.lib.iolib.np2gdal_dtype(d)

Get GDAL RasterBand datatype that corresponds with NumPy datatype Input should be numpy array or numpy dtype

pygeotools.lib.iolib.readcsv(fn)

Wrapper to read arbitrary csv, check for header

Needs some work to be more robust, quickly added for demcoreg sampling

pygeotools.lib.iolib.replace_ndv(b, new_ndv)

pygeotools.lib.iolib.set_ndv(dst_fn, ndv)

pygeotools.lib.iolib.setstripe(dir, threads=2)

pygeotools.lib.iolib.writeGTiff(a, dst_fn, src_ds=None, bnum=1, ndv=None, gt=None, proj=None, create=False, sparse=False)

Write input array to disk as GeoTiff

Parameters:

• a (np.array or np.ma.array) – Input array
• dst_fn (str) – Output filename
• src_ds (GDAL Dataset, optional) – Source Dataset to use for creating copy
• bnum (int, optional) – Output band
• ndv (float, optional) – Output NoData Value
• gt (list, optional) – Output GeoTransform
• proj (str, optional) – Output Projection (OGC WKT or PROJ.4 format)
• create (bool, optional) – Create new dataset
• sparse (bool, optional) – Output should be created with sparse options

pygeotools.lib.iolib.write_recarray(outfn, ra)

pygeotools.lib.iolib.writevrt(out_csv, srs='EPSG:4326', x='field_1', y='field_2')

Write out a vrt to accompany a csv of points