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Added RasterReader.copy_to() utility based on SQL command COPY TO and PostGIS Raster functions ST_As<FORMAT> and outputs rasters to hex-encoded plain text or binary raster file.

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git-svn-id: http://svn.osgeo.org/postgis/trunk@10805 b70326c6-7e19-0410-871a-916f4a2858ee
This commit is contained in:
Mateusz Loskot 2012-12-06 17:39:04 +00:00
parent 46d65ae839
commit d9eb8fd557
1 changed files with 36 additions and 4 deletions
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40
raster/scripts/python/rtreader.py
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@ -74,6 +74,39 @@ class RasterReader(object):
def get_value(self, band, x, y):
return self._query_value(band, x, y)
def copy_to(self, file, raster_format='TIFF', output_format='HEX', sep='\t'):
"""
Proxy for SQL command COPY TO,
Converts selected rasters to specified raster_format with output sent either to
single hex-based plain text file or one or more binary files in raster_format,
one raster binary file per tuple from the raster table.
The BIN output uses HEX output as intermediate stage.
raster_format - TIFF|JPEG|PNG
output_format - HEX|BIN; BIN is a binary file in raster_format
sep - if output_format=HEX, separates rid value from hex-encoded binary.
"""
import os.path
filehex = file # No extension added, may be user-defiened
with open(filehex, 'w') as f:
select = "SELECT rid, encode(ST_As%s(%s), 'hex') As rt FROM %s" % (raster_format, self._column, self._table)
if self._where is not None and len(self._where) > 0:
select += ' WHERE %s' % self._where
sql = "COPY (%s) TO STDOUT (DELIMITER '%s')" % (select, sep)
cur = self._conn.cursor()
cur.copy_expert(sql, f)
if output_format == 'BIN':
import binascii
with open(filehex, 'r') as f:
dirname = os.path.dirname(file)
ext = raster_format.lower()
for line in f.readlines():
rid, raster = line.split()
filebin = self._table + '_' + self._column + '_' + rid + '.' + ext
filebin = os.path.join(dirname, filebin)
with open(filebin, 'w+') as fbin:
fbin.write(binascii.unhexlify(raster))
# Private methods
def _log(self, m):
@ -103,7 +136,7 @@ class RasterReader(object):
try:
if self._conn is None:
self._conn = psycopg2.connect(self._connstr)
except Exception, e:
except Exception as e:
raise RasterError("Falied to connect to %s: %s" % (self._connstr, e))
def _query_single_row(self, sql):
@ -113,9 +146,8 @@ class RasterReader(object):
try:
cur = self._conn.cursor()
cur.execute(sql)
except Exception, e:
raise RasterError("Failed to execute query %s: %s" % (sql,
e))
except Exception as e:
raise RasterError("Failed to execute query %s: %s" % (sql, e))
row = cur.fetchone()
if row is None: