Python使用numpy模块创建数组操作示例

import numpy as np
ndarray1 = np.array([1, 2, 3, 4])
ndarray2 = np.array(list('abcdefg'))
ndarray3 = np.array([[11, 22, 33, 44], [10, 20, 30, 40]])

ndarray4 = np.zeros(10)
ndarray5 = np.zeros((3, 3))
ndarray6 = np.zeros_like(ndarray5) # 按照 ndarray5 的shape创建数组
# 打印数组元素类型
print("以下为数组类型:")
print('ndarray4:', type(ndarray4))
print('ndarray5:', type(ndarray5))
print('ndarray6:', type(ndarray6))
print("-------------")
print("以下为数组元素类型:")
print('ndarray4:', ndarray4.dtype)
print('ndarray5:', ndarray5.dtype)
print('ndarray6:', ndarray6.dtype)
print("-------------")
print("以下为数组形状:")
print('ndarray4:', ndarray4.shape)
print('ndarray5:', ndarray5.shape)
print('ndarray6:', ndarray6.shape)

#创建数组，元素默认值是0
ndarray7 = np.ones(10)
ndarray8 = np.ones((3, 3))
#修改元素的值
ndarray8[0][1] = 999
ndarray9 = np.ones_like(ndarray5) # 按照 ndarray5 的shape创建数组

ndarray10 = np.empty(5)
ndarray11 = np.empty((2, 3))
ndarray12 = np.empty_like(ndarray11)

ndarray13 = np.arange(10)     #产生0-9共10个元素
ndarray14 = np.arange(10, 20)    #产生从10-19共10个元素
ndarray15 = np.arange(10, 20, 2)   #产生10 12 14 16 18, 2为step 间隔为2
print('ndarray14的形状:', ndarray14.shape) #ndarray15的长度
ndarray14.reshape((2, 5))     #将其形状改变为(2, 5) 分2部分 每份5个

ndarray16 = np.eye(5)