Rename netCDF dimensions

Question

I want to reanme the dimensions of a .nc file, from 'latitude' to 'lat' and from 'longitude to lon', to later be able to combine it with another .nc dataset. This is how my .nc file looks like:

Dimensions:    (time: 1, latitude: 1037, longitude: 1345)
Coordinates:
  * latitude   (latitude) float32 37.7 37.7 37.69 37.69 ... 35.01 35.0 35.0
  * time       (time) datetime64[ns] 2021-11-23
  * longitude  (longitude) float32 -9.001 -8.999 -8.996 ... -5.507 -5.504 -5.501

Data variables:
    CHL        (time, latitude, longitude) float32 ...

Attributes: (12/38)
    FROM_ORIGINAL_FILE__Metadata_Conventions:  Unidata Dataset Discovery v1.0
    keywords:                                  satellite,observation,ocean
    summary:                                   These data are Level-3 satelli...
    history:                                   1637676190 Created by composit...
    netcdf_file_type:                          NETCDF4_CLASSIC
    contact:                                   email: cmems@pml.ac.uk
    ...                                        ...
    start_date:                                2021-11-23
    start_time:                                00:00:00 UTC
    stop_date:                                 2021-11-23
    stop_time:                                 23:59:00 UTC
    _CoordSysBuilder:                          ucar.nc2.dataset.conv.CF1Conve...
    source:      

I tired using the following code found here:

from netCDF4 import Dataset
path='dataset-oc-atl-chl-olci-l3-chl_300m_daily-rt_1637778183019.nc'
f=Dataset(path,'r+')
f.renameDimension(u'longitude',u'lon')
f.renameVariable(u'longitude',u'lon')
f.renameDimension(u'latitude',u'lat')
f.renameVariable(u'latitude',u'lat')
f.close()

But the following error pops up:

KeyError: 'longitude not a valid dimension name'

Any ideas? Thank you!

Answer 1

First, thanks to @user2314737 I figured out that one of the files I was trying to rename was corrupt and the dictionary containing the dimensions was empty. I updated the file and found this simple solution to rename the dimensions:

ds1 = xr.open_dataset("dataset-oc-atl-chl-olci-l3-chl_300m_daily-rt_1637844102280.nc")
ds1

[Out]

<xarray.Dataset>
Dimensions:  (time: 1, latitude: 1037, longitude: 1345)
Coordinates:
  * latitude      (latitude) float32 37.7 37.7 37.69 37.69 37.69 ... 35.01 35.01 35.0 35.0
  * time     (time) datetime64[ns] 2021-11-23
  * longitude      (longitude) float32 -9.001 -8.999 -8.996 -8.993 ... -5.507 -5.504 -5.501
Data variables:
    CHL      (time, lat, lon) float32 ...
Attributes: (12/38)

The solution is:

ds1 = ds1.rename({'latitude': 'lat','longitude': 'lon'})

[Out]

<xarray.Dataset>
Dimensions:  (time: 1, lat: 1037, lon: 1345)
Coordinates:
  * lat      (lat) float32 37.7 37.7 37.69 37.69 37.69 ... 35.01 35.01 35.0 35.0
  * time     (time) datetime64[ns] 2021-11-23
  * lon      (lon) float32 -9.001 -8.999 -8.996 -8.993 ... -5.507 -5.504 -5.501
Data variables:
    CHL      (time, lat, lon) float32 ...
Attributes: (12/38)