Python 从 .netcdf 列更改 xarray 维度坐标值

Question

I have two datasets:

• An dataframe df with converted time data
• A.netCDF file on my disk, loaded as an xarray.Dataset ds.

The.netcdf/xarray has 3 dimensions: time, latitude, longitude.

I want to update the time dimension in the xarray.Dataset with the converted values of the dataframe. Currently, I am doing it like this:

import xarray as xr

# load netcdf
ds = xr.open_dataset('msr.nc', decode_times= False) # as the time data is not correct

# Copy converted time
ds['time'] = df['conv_time']

The coordinates get updated as another column, but the original stays.

The xarray.Dataset looks as the following:

> Dimensions:  dim_0: 504 longitude: 720 latitude: 361 time: 504
> Coordinates:
time       (dim_0)      datetime64[ns]  1979-01-15 ... 2020-12-15
longitude  (longitude)  float32        -179.5 -179.0 ... 179.5 180.0
latitude   (latitude)   float32        -90.0 -89.5 -89.0 ... 89.5 90.0
dim_0      (dim_0)      int64           0 1 2 3 4 5 ... 499 500 501 502 503

It seems it creates a new time dimension and makes a new one(dim_0) of the old one, but doesn't correctly make the link with the updated datetime coordinates.

The file now has 4 dimensions, but only 3 coordinates and it still links to the wrong one.

I have tried creating a new coordinate, deleting the other one, swapping the names. But this all doesn't work. I just want to simply change the values of the time dimension to the ones I already have.

How do I fix this to make sure the updated time is the only time dimension?

Answer 1

It was very simple, and use:

ds["time"] = ("time", updated_times)