Created
June 22, 2013 10:09
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example of sum()
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#! /usr/bin/python | |
# -*- coding: utf-8 -*- | |
import numpy as np | |
## 2x4の行列を作成 | |
A = np.arange(8).reshape(2,4) | |
# >>> A | |
# array([[0, 1, 2, 3], | |
# [4, 5, 6, 7]]) | |
## 列方向の和をとり,行ベクトルを出力 | |
row_sum = np.sum(A, axis=0) | |
# >>> row_sum | |
# array([ 4, 6, 8, 10]) | |
## 行方向の和をとり,列ベクトルを出力 | |
col_sum = np.sum(A, axis=1) | |
# >>> col_sum | |
# array([ 6, 22]) | |
## 要素の総和を取る | |
A.sum() | |
>>> A.sum() | |
28 | |
## col_sumを求めているのと同義の文 | |
B = np.zeros(A.shape[0]) | |
for i in range( A.shape[0] ) : | |
B[i] = A[i].sum() | |
# >>> B | |
# array([ 6., 22.]) | |
## row_sumを求めているのと同義の文 | |
C = np.zeros(A.shape[1]) | |
for i in range( A.shape[1] ) : | |
C[i] = A[:,i].sum() | |
# >>> C | |
# array([ 4., 6., 8., 10.]) |
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