Value error in multiplying xarray variable with 2D numpy array

Question

import xarray as xr
xr.open_dataset(path_netcdf, chunks={'time': 10})
flow_data = hndl_tran['val']
new_arr = flow_data * vba

I get this error:

*** ValueError: total size of new array must be unchanged

Here are the shapes of the 2 arrays:

flow_data.shape
(1165, 720, 1440)

vba.shape
(720L, 1440L)

How can I fix this error?

maxymoo · Accepted Answer · 2016-02-24 04:10:43Z

1

Make your numpy into an xarray object before you do the multiplication:

flow_data = xr.DataArray(hndl_tran['val'])

or vice versa

flow_data = np.array(flow_data)

edited Feb 24, 2016 at 4:10

answered Feb 24, 2016 at 3:11

maxymoo

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3 Comments

user308827 Over a year ago

please have a look at a corollary: stackoverflow.com/questions/35593005/…

maxymoo Over a year ago

hmm no idea what's causing this, can you try it the other way around, converting the xarray to numpy array?

user308827 Over a year ago

that wouldn't work, if i try to convert the xarray to numpy array, the resulting numpy array is too big to fit in memory. thanks for looking :)

Maximilian · Accepted Answer · 2016-02-24 17:51:09Z

1

Building on @maxymoo's answer, you want to convert to a DataArray, but also supply dims, so operations with other arrays will work flow_data = xr.DataArray(hndl_tran['val'], dims=['date', 'id']), replacing date & id with the appropriate names

answered Feb 24, 2016 at 17:51

Maximilian

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