CODEWITHSUNDEEP
python
Mikhail Genkin
Mikhail Genkin

Reputation: 3460

Using names-values defined in a dictionary with numpy.savez

I am struggling with the following problem: given a dictionary with an numpy array as a value, for example, a={'xarray':np.ones((2,2))}, I want to save the array into npz file with name from the dictionary key:

np.savez('test.npz',a.keys()=a['xarray'])

The error is in a.keys: 

SyntaxError: keyword can't be an expression.

I need to convert the key into an expression somehow. I tried to use eval function but didn't succeed.

Thanks, Mikhail

Edit:

In order to clarify things, I want the result to be equivalent to the following:

np.savez('test.npz', xarray = np.ones((2,2)))

The name of my array is specified in the first key of the dictionary, while the array itself in the first value: a={'xarray':np.ones((2,2))}.

Attempting: np.savez('test.npz',format(list(a.keys())[0])=list(a.values())[0]) returns again SyntaxError: keyword can't be an expression

Upvotes: 2

Views: 871

Answers (1)

Dawid_Sielski
Dawid_Sielski

Reputation: 384

If I understand you correctly you should try something line that: np.savez('{}.npz'.format(list(a.keys())[0])). This will set a filename to a first key in a given dictionary.

The error that you get is correct since you are trying to set a.keys() to be the value of a['xarray'] which is an expression. Moreover, to my very best knowledge python will not allow that.

Edit: I am just after the lecture of what np.savez function does and I misunderstood you. So the correct thing (if I am correct now) is to do this:

kwargs = {key: a[key] for key in a.keys()}
np.savez('test.npz', **kwargs)

Please try and say if this is what you want :)

Edit 2: For having only first key:

kwargs = {key: a[key] for key in [list(a.keys())[0]]}
np.savez('test.npz', **kwargs)

Upvotes: 3

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