user552231 - 1 year ago 249

Python Question

I need to take the nanmean of columns in matrix in python. for example:

`import numpy as np`

a=[[np.nan,2,3,4],[5,np.nan,7,8],[9,10,np.nan,12]]

a=

matrix([[ nan, 2., 3., 4.],

[ 5., nan, 7., 8.],

[ 9., 10., nan, 12.]])

I want something like np.nanmean(a) that will return [7,6,5,8], the current command returns 6.66

Thank you

Ariel

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Answer Source

You need to use the keyword `axis=0`

to achieve the result!

```
import numpy as np
a=[[np.nan,2,3,4],[5,np.nan,7,8],[9,10,np.nan,12]]
>>> np.nanmean(a, axis=0)
array([ 7., 6., 5., 8.])
```

See the docs for details.

Omitting the keyword will give the mean of all entries of the matrix that are not `np.nan`

.

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