Open and plot a large raster with Python xarray

Question

I have an ASCII Esri file of the type:
ncols 5201
nrows 4001
xllcorner -65
yllcorner -35
cellsize 0.025
NODATA_value -9999
-9999 -9999 -9999 255 256 -9999 -9999 ...
-9999 -9999 -9999 -9999 -9999 -9999 -9999 ...
-9999 -9999 -9999 -9999 255 -9999 230 ...
...

I'm trying to import it with rioxarray by doing:
import xarray as xr
import rioxarray

da = rioxarray.open_rasterio('data.asc',masked=True)
da.plot()

What I get is a graph with the correct coordinates, but no data shown:

Do you know why this is?
da is imported as an xarray.DataArray and looks like this:

snowman2 · Accepted Answer

This should do the trick:
import rioxarray

da = rioxarray.open_rasterio('data.asc', masked=True)
da.squeeze().plot.imshow()

gioarma · Answer

Turns out the data were just too many and the xarray plot function could not handle it. By selecting a chunk of size not much smaller than the original data, the plot looks fine.
Note that by using rasterio's show function instead there is no problem plotting this amount of data:
from rasterio.plot import show
show(rasterio.open('data.asc'))

Open and plot a large raster with Python xarray

2 Answers

Add your own answers!

Ask a Question