Select a column from an xarray

user_5431734 0
Viewed 956

How do you select a column from an xarray.DataArray please? This is how I am doing the xarray

import xarray as xr
import numpy as np
import pandas as pd

my_data = np.random.rand(5,2)
da = xr.DataArray(my_data, 
                  coords={'my_id':np.arange(my_data.shape[0]),
                         'columns': ['x', 'y']},
                  dims=['my_id', 'columns'])

and I want to select column x. If that was a dataframe

df = pd.DataFrame(my_data, columns=['x','y'])

i am looking for the equivalent of df['x']

Am I defining the DataArray the wrong way?

python-xarray python-3.x python
3 Answers

Ah ok, i think i got it:

da.sel(columns='x')
user_54317340

You can use pandas-like .loc as suggested in docs:

da.loc[:, ['x']]

<xarray.DataArray (my_id: 5, columns: 1)>
array([[ 0.534358],
       [ 0.113875],
       [ 0.905085],
       [ 0.96994 ],
       [ 0.548338]])
Coordinates:
  * my_id    (my_id) int32 0 1 2 3 4
  * columns  (columns) <U1 'x'
user_58110780

Straight from the docs: http://xarray.pydata.org/en/stable/generated/xarray.DataArray.to_pandas.html

import xarray as xr
import numpy as np
import pandas as pd

my_data = np.random.rand(5,2)
da = xr.DataArray(my_data, 
                  coords={'my_id':np.arange(my_data.shape[0]),
                         'columns': ['x', 'y']},
                  dims=['my_id', 'columns'])

df = da.to_pandas()

df['x']

Result

df['x']

Out[27]: 
my_id
0    0.752056
1    0.048029
2    0.145835
3    0.083147
4    0.618351
Name: x, dtype: float64
user_92008340
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