How can I check whether the numpy array is empty or not?

问题:

How can I check whether the numpy array is empty or not?

I used the following code, but this is fail if the array contains a zero.

if not self.Definition.all(): 

is this the solution?

if self.Definition == array( [] ): 

回答1:

You can always take a look at the .size attribute:

import numpy as np a = np.array([]) print a.size # 0 

回答2:

http://www.scipy.org/Tentative_NumPy_Tutorial#head-6a1bc005bd80e1b19f812e1e64e0d25d50f99fe2

NumPy's main object is the homogeneous multidimensional array. In Numpy dimensions are called axes. The number of axes is rank. Numpy's array class is called ndarray. It is also known by the alias array. The more important attributes of an ndarray object are:

ndarray.ndim
the number of axes (dimensions) of the array. In the Python world, the number of dimensions is referred to as rank.

ndarray.shape
the dimensions of the array. This is a tuple of integers indicating the size of the array in each dimension. For a matrix with n rows and m columns, shape will be (n,m). The length of the shape tuple is therefore the rank, or number of dimensions, ndim.

ndarray.size
the total number of elements of the array. This is equal to the product of the elements of shape.

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