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80 lines
2.6 KiB
ReStructuredText
80 lines
2.6 KiB
ReStructuredText
Datasets and ndarrays
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=====================
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Dataset objects provide read, read-write, and write access to raster data files
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and are obtained by calling ``rasterio.open()``. That function mimics Python's
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built-in ``open()`` and dataset objects mimic Python ``file`` objects.
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.. code-block:: pycon
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>>> import rasterio
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>>> dataset = rasterio.open('rasterio/tests/data/RGB.byte.tif')
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>>> print dataset
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<open RasterReader name='rasterio/tests/data/RGB.byte.tif' mode='r'>
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>>> dataset.name
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'rasterio/tests/data/RGB.byte.tif'
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>>> print dataset.mode
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r
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>>> print dataset.closed
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False
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If you attempt to open a nonexistent dataset, ``rasterio.open()`` does the same
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thing as ``open()``: raising an exception immediately.
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.. code-block:: pycon
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>>> open('/lol/wut.tif')
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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IOError: [Errno 2] No such file or directory: '/lol/wut.tif'
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>>> rasterio.open('/lol/wut.tif')
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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IOError: no such file or directory: '/lol/wut.tif'
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Datasets generally have one or more bands (or layers) and these are indexed starting with the number 1. The first band of a file can be read like this:
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.. code-block:: pycon
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>>> dataset.read_band(1)
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array([[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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...,
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0]], dtype=uint8)
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The returned object is a Numpy (N-dimensional; 2 in this case) ndarry.
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indexes of all a dataset's bands can be had from a dataset's ``indexes``
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attribute. Read all band data from a dataset like this:
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.. code-block:: pycon
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>>> dataset.indexes
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[1, 2, 3]
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>>> [dataset.read_band(i) for i in dataset.indexes]
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[array([[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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...,
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0]], dtype=uint8),
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array([[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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...,
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0]], dtype=uint8),
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array([[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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...,
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0],
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[0, 0, 0, ..., 0, 0, 0]], dtype=uint8)]
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