Geografic-Information-System/lib/python/array.py

"""!@package grass.script.array

@brief GRASS Python scripting module (rasters with numpy)

Functions to use GRASS rasters with NumPy.

Usage:

@code
from grass.script import array as garray

    map = 'elevation'
    x = garray.array()
    x.read(map)
    # calculate something on array
    x[...] = x / 50.
    x.write(map + ".new")
@endcode

(C) 2010-2011 by Glynn Clements and the GRASS Development Team
This program is free software under the GNU General Public
License (>=v2). Read the file COPYING that comes with GRASS
for details.

@author Glynn Clements
"""

import os
import numpy

import core as grass

class array(numpy.memmap):
    def __new__(cls, dtype = numpy.double):
        """!Define new numpy array

        @param cls
        @param dtype data type (default: numpy.double)
        """
	reg = grass.region()
	r = reg['rows']
	c = reg['cols']
	shape = (r, c)
        
	filename = grass.tempfile()
        
	self = numpy.memmap.__new__(
	    cls,
	    filename = filename,
	    dtype = dtype,
	    mode = 'w+',
	    shape = shape)
        
	self.filename = filename
	return self
    
    def _close(self):
	numpy.memmap._close(self)
	if isinstance(self, array):
	    grass.try_remove(self.filename)

    def read(self, mapname, null = None):
        """!Read raster map into array

        @param mapname name of raster map to be read
        @param null null value

        @return 0 on success
        @return non-zero code on failure
        """
	kind = self.dtype.kind
	size = self.dtype.itemsize
        
	if kind == 'f':
	    flags = 'f'
	elif kind in 'biu':
	    flags = 'i'
	else:
	    raise ValueError(_('Invalid kind <%s>') % kind)
        
	if size not in [1,2,4,8]:
	    raise ValueError(_('Invalid size <%d>') % size)
        
	return grass.run_command(
	    'r.out.bin',
	    flags = flags,
	    input = mapname,
	    output = self.filename,
	    bytes = size,
	    null = null,
	    quiet = True)
	
    def write(self, mapname, title = None, null = None, overwrite = None):
        """!Write array into raster map

        @param mapname name for raster map
        @param title title for raster map
        @param null null value
        @param overwrite True for overwritting existing raster maps

        @return 0 on success
        @return non-zero code on failure
        """
	kind = self.dtype.kind
	size = self.dtype.itemsize
        
	if kind == 'f':
	    if size == 4:
		flags = 'f'
	    elif size == 8:
		flags = 'd'
	    else:
		raise ValueError(_('Invalid FP size <%d>') % size)
	    size = None
	elif kind in 'biu':
	    if size not in [1,2,4]:
		raise ValueError(_('Invalid integer size <%d>') % size)
	    flags = None
	else:
	    raise ValueError(_('Invalid kind <%s>') % kind)
        
	reg = grass.region()
        
	return grass.run_command(
	    'r.in.bin',
	    flags = flags,
	    input = self.filename,
	    output = mapname,
	    title = title,
	    bytes = size,
	    anull = null,
	    overwrite = overwrite,
	    verbose = True,
	    north = reg['n'],
	    south = reg['s'],
	    east  = reg['e'],
	    west  = reg['w'],
	    rows  = reg['rows'],
	    cols  = reg['cols'])