CODEWITHSUNDEEP
projectionshapefilegeopandas
Topher Hughes
Topher Hughes

Reputation: 365

Geopandas to_file gives blank prj file

I am trying to use GeoPandas for a (only slightly) more complex project, but at the moment I'm failing to write out a simple shapefile with a single point in it in a projected manner.

The following code results in a shapefile that looks generally good - but the .prj is empty:

import pandas as pd
from geopandas import GeoDataFrame
from shapely.geometry import Point

df=pd.read_csv("richmond.csv")
geometry = [Point(xy) for xy in zip(df.x, df.y)]
crs = {'init': 'epsg:4326'}
geo_df = GeoDataFrame(df, crs=crs, geometry=geometry)

geo_df.to_file("geopan.shp")

The csv is 2 row and 2 columns (header row, then lon and lat in 2nd row):

a really basic csv

Am I missing something obvious? I've hunted through stackoverflow, the geopandas docs, etc. All seem to imply to_file() should work just fine.

In the long run, the goal is to create a few functions for my students to use in a lab - one that draws a line along a lat or lon the width / height of the US, another that clips the line to polygons (the states), so that the students can figure out the widest spot in each state as a gentle introduction to working with spatial data. I'm trying to avoid arcpy as it's Python 2, and I thought (and think) I was doing the right thing by teaching them the ways of Python 3. I'd like them to be able to debug their methodologies by being able to open the line in Arc though, hence this test.

Upvotes: 3

Views: 2016

Answers (3)

daniel-cheng
daniel-cheng

Reputation: 152

Another user and I had a similar issue using fiona, and the issue for me was the GDAL_DATA environmental variable not being set correctly. To reiterate my answer there: For reference, I'm using Anaconda, the Spyder IDE, Fiona 1.8.4, and Python 3.6.8, and GDAL 2.3.3.

While Anaconda usually sets the GDAL_DATA variable upon entering the virtual environment, using another IDE like Spyder will not preserve it, and thus causes issues where fiona (and I assume Geopandas) can't export the CRS correctly.

You can test this fix by trying to printing out a EPSG to WKT transformation before & after setting the GDAL_DATA variable explictly.

Without setting GDAL_DATA:

import os
print('GDAL_DATA' in os.environ)
from osgeo import osr
srs = osr.SpatialReference() # Declare a new SpatialReference 
srs.ImportFromEPSG(3413) # Import the EPSG code into the new object srs
print(srs.ExportToWkt()) # Print the result before transformation to ESRI WKT (prints nothing)

Results in:

False

With setting GDAL_DATA:

import os
os.environ['GDAL_DATA'] = 'D:\\ProgramData\\Anaconda3\\envs\\cfm\\Library\\share\\gdal'
print('GDAL_DATA' in os.environ)
from osgeo import , osr
srs = osr.SpatialReference() # Declare a new SpatialReference 
srs.ImportFromEPSG(3413) # Import the EPSG code into the new object srs
print(srs.ExportToWkt()) # Print the result before transformation to ESRI WKT (prints nothing)

Results in:

True
PROJCS["WGS 84 / NSIDC Sea Ice Polar Stereographic North",GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4326"]],PROJECTION["Polar_Stereographic"],PARAMETER["latitude_of_origin",70],PARAMETER["central_meridian",-45],PARAMETER["scale_factor",1],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["X",EAST],AXIS["Y",NORTH],AUTHORITY["EPSG","3413"]]

Upvotes: 0

Topher Hughes
Topher Hughes

Reputation: 365

So, after playing with this, I've determined that under the current version of Anaconda the problem is with crs = {'init': 'epsg:4326'} on Windows machines. This works fine on Macs, but has not worked on any of my or my students' Windows systems. Changing this line to make use of the proj4 string crs = {'proj': 'latlong', 'ellps': 'WGS84', 'datum': 'WGS84', 'no_defs': True} instead works just fine. More of a workaround than an actual solution, but, it seems to consistently work.

Upvotes: 3

lukaszKielar
lukaszKielar

Reputation: 541

I'm always using from_epsg function from fiona library.

>>> from fiona.crs import from_epsg
>>> from_epsg(4326)
{'init': 'epsg:4326', 'no_defs': True}

I've never had any problems using it. Keep it mind that some local projections are missing, but it shouldn't be a problem in your case.

Upvotes: 1

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