CODEWITHSUNDEEP
python-3.xpython-2.7numpy
MH.AI.eAgLe
MH.AI.eAgLe

Reputation: 673

Extracting values of a key from an array of dictionaries

I want to read from a .npy file to do some signal processing tasks but during this task I received this error:

IndexError: only integers, slices (:), ellipsis (...), numpy.newaxis (None) and integer or boolean arrays are valid indices

this is my code:

import numpy as np
import matplotlib.pyplot as plt


file  = '/signal/data.npy'
d = np.load(file,allow_pickle=True,encoding = 'latin1')

d['soma'][0]

There are same questions but I could not use them to solve this one.So can anyone help me to fix It? Thanks

This the error: enter image description here

This is part of my data( d is equal to res):

enter image description here

Upvotes: 0

Views: 197

Answers (2)

jdragon
jdragon

Reputation: 26

your data consists of arrays of dictionaries. for each array you have some keys with its values. the solution as @ hpaulj said is:

   res[array_index]["your_key"]

Upvotes: 1

Ehsan
Ehsan

Reputation: 12407

You have a numpy array d and you are trying to access e.g. "soma" index which is not possible. Numpy indexing rule is:
only integers, slices (:), ellipsis (...), numpy.newaxis (None) and integer or boolean arrays are valid indices.

If your numpy array includes dictionaries, you need to extract dictionaries. d['soma'] does not extract elements of numpy array.
This loops over array d and extracts the first element of values of key 'soma' for all dictionaries in d that has key 'soma': 

lfp = [i['soma'][0] for i in d if 'soma' in i]

And if it is a dataframe instead of numpy array, try: 

d = pd.read_pickle(file)

Upvotes: 1

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