Value NAN in NetCDF4 file for lat&lon using Python

Question

I have two files in NetCDF4 (latlon and other file without latlon).

I open the two files in the same code and I choose one variable and the two variable lon and lat. When I write lon I have the value nan and I don't know why.

The two files have same dimensions (size) and same dimensions for variables all I need is to show the value of lat&lon when I open the two files. How can I do it?

In [54]: import numpy as np
 ...: import netCDF4
 ...: 
 ...: 
 ...: fic1='/data/latlon_+000.0_globe.nc'
 ...: 
 ...: nc1 = netCDF4.Dataset(fic1,'r')
 ...: 
 ...: lon = nc1.variables['lon'][:]
 ...: lat = nc1.variables['lat'][:]
 ...: 
 ...: fic='/data/Mmultic3kmNC4_msg04_201905080200
 ...: .nc'
 ...: 
 ...: 
 ...: nc = netCDF4.Dataset(fic,'r')
 ...: IR=nc.variables['IR_108'][:]
 ...: 
 ...: 
In [55]: 
In [55]: lon
Out[55]: 
masked_array(
 data=[[nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan],
 ...,
 [nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan]],
 mask=False,
 fill_value=1e+20,
 dtype=float32)
In [56]: lat
Out[56]: 
masked_array(
 data=[[nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan],
 ...,
 [nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan],
 [nan, nan, nan, ..., nan, nan, nan]],
 mask=False,
 fill_value=1e+20,
 dtype=float32)
In [57]: 

How I can get value of lat & lon?

• Hicham Zouarhi: your code seems right, could you provide your sample data for tests ?
• Sarah Tohami: @HichamZouarhi you can get data here latlon[drive.google.com/file/d/1UjTv0aYttGYoVaUUAT9gjEPuTgcOvOHj/view] and other file data [drive.google.com/file/d/1IT-F7AbIx4bCjMLosjBx4F4UCoIX5DU0/view] thank you
• Hicham Zouarhi: there are indeed no data ( or corrupted data since many attributes of the variables are missing ) in the first file ( the one with lat lon ), are those coordinates supposed to refer to X and Y on the second file ?
• Sarah Tohami: yes the 2 files have same dimensions when you open the file1 latlon with the second you can get value of lon & lat i don't know how but yesterday i did it and today i can get the value :!!

Answer 1

after checking the contents of the 2 files, there seems to be a problem with the dimensions of the one with lat lon variables since the attribute current_shape = (3712, 3712) for lat and lon while it should be (3712,).

The file may be corrupted and you'll have to create it again from the X and Y attributes of the second file since they are linked.

to do so you can start with this answer , you will also need to transform the projected coordinates to lat lon, and for that you can use pyproj