将列表转换为 numpy 数组

Question

I have managed to load images in a folder using the command line sklearn: load_sample_images()

I would now like to convert it to a numpy.ndarray format with float32 datatype

I was able to convert it to np.ndarray using : np.array(X) , however np.array(X, dtype=np.float32) and np.asarray(X).astype('float32') give me the error:

 ValueError: setting an array element with a sequence.

Is there a way to work around this?

from sklearn_theano.datasets import load_sample_images
import numpy as np  

kinect_images = load_sample_images()
X = kinect_images.images

X_new = np.array(X)  # works
X_new = np.array(X[1], dtype=np.float32)  # works

X_new = np.array(X, dtype=np.float32)  # does not work

Answer 1

If you have a list of lists, you only needed to use ...

import numpy as np
...
npa = np.asarray(someListOfLists, dtype=np.float32)

per this LINK in the scipy / numpy documentation. You just needed to define dtype inside the call to asarray.