如何获取数组的维数?例如，这是2x2:
a = np.array([[1,2],[3,4]])
当前回答
a.shape只是np.info()的一个限定版本。看看这个:
import numpy as np
a = np.array([[1,2],[1,2]])
np.info(a)
Out
class: ndarray
shape: (2, 2)
strides: (8, 4)
itemsize: 4
aligned: True
contiguous: True
fortran: False
data pointer: 0x27509cf0560
byteorder: little
byteswap: False
type: int32
其他回答
你可以用.ndim表示尺寸，用.shape来知道确切的尺寸:
>>> var = np.array([[1,2,3,4,5,6], [1,2,3,4,5,6]])
>>> var.ndim
2
>>> varshape
(2, 6)
你可以使用.重塑函数改变尺寸:
>>> var_ = var.reshape(3, 4)
>>> var_.ndim
2
>>> var_.shape
(3, 4)
rows = a.shape[0] # 2
cols = a.shape[1] # 2
a.shape #(2,2)
a.size # rows * cols = 4
a.shape只是np.info()的一个限定版本。看看这个:
import numpy as np
a = np.array([[1,2],[1,2]])
np.info(a)
Out
class: ndarray
shape: (2, 2)
strides: (8, 4)
itemsize: 4
aligned: True
contiguous: True
fortran: False
data pointer: 0x27509cf0560
byteorder: little
byteswap: False
type: int32
使用.shape:
In: a = np.array([[1,2,3],[4,5,6]])
In: a.shape
Out: (2, 3)
In: a.shape[0] # x axis
Out: 2
In: a.shape[1] # y axis
Out: 3
shape方法要求a是Numpy ndarray。但是Numpy也可以计算纯python对象的可迭代对象的形状:
np.shape([[1,2],[1,2]])
