Hi Evan,
thank you very much, this is indeed a problem related to locale.
Adding the 2 lines you recommended solved the problem. I looked for a
more permanent way to solve this problem and found this post :
http://stefaanlippens.net/pylabllocaleproblem
A way to fix the problem more permanently is to set the environment
variable LC_NUMERIC to C :
> export LC_NUMERIC="C"
for example in the .bashrc.
It solves the problem for this script, now I hope it won't create other
problems!
Amaury
Le 10/08/2015 14:18, Even Rouault a écrit :
Le lundi 10 août 2015 12:27:49, Amaury Dehecq a écrit :
Hi all,
I noticed that osgeo.ogr.Feature.GetField behaves differently when a
matplotlib function is called. In particular, fields of type "Real"
don't return the same value when called before or after the use of
matplotlib functions. See for example the script below that extract the
fields values from an ESRI shapefile :
"""
import matplotlib.pyplot as plt
from osgeo import ogr
#Read ESRI shapefile
filename='/disk/L0data/GLIMS/RGI_5.0/all_asia.shp'
ds = ogr.Open(filename,0)
layer = ds.GetLayer()
#Comment/uncomment this line
#plt.figure()
#plt.show()
#Extract field number 5 information (central longitude)
index=5
layerDefinition = layer.GetLayerDefn()
name= layerDefinition.GetFieldDefn(index).GetName()
print "Name : %s " %name
fieldTypeCode = layerDefinition.GetFieldDefn(index).GetType()
print "Type : %s"
%layerDefinition.GetFieldDefn(index).GetFieldTypeName(fieldTypeCode)
print "Width : %i" %layerDefinition.GetFieldDefn(index).GetWidth()
#Extract feature field values
for i in xrange(5):
feat = layer.GetNextFeature()
print feat.GetField(name)
"""
This script returns :
/Name : CenLon //
//Type : Real//
//Width : 14//
//79.4939//
//77.9513//
//77.9295//
//77.9237//
//77.9141/
But when the 2 matplotlib lines are uncommented, it returns :
/Name : CenLon //
//Type : Real//
//Width : 14//
//79.0//
//77.0//
//77.0//
//77.0//
//77.0//
/
It seems that the values are truncated. Has anyone observed the same
problem? Are there any incompatibilities between matplotlib and OGR?
Amaury,
This looks like a locale related problem where matplotlib would install a non
C locale with a decimal separator that isn't point. There have been a lot of
work done in GDAL 2.0 to be immune to the locale. However the shapefile driver
in reading should have been immune to non C locales for even a longer time, so
I'm not sure why you see this.
As a potential workaround you could try to do the following:
import locale
locale.setlocale(locale.LC_ALL, 'C')
just after the matplotlib calls.
Even
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