python中axis啥意思

import numpy as np# 创建一个 2x3 数组arr = np.array([[1, 2, 3], [4, 5, 6]])# 求每一行的和（axis=0）row_sums = np.sum(arr, axis=0)  # [10 15 21]# 求每一列的和（axis=1）col_sums = np.sum(arr, axis=1)  # [6 15]# 求整个数组的和（axis=None）total_sum = np.sum(arr, axis=None)  # 21