Python 转换矩阵

问题描述

我有一个看起来像这样的列表:

I have a list looking like this:

[2, 1, 3, 1, 2, 3, 1, 2, 2, 2]

[2, 1, 3, 1, 2, 3, 1, 2, 2, 2]

我想要的是一个转换矩阵，它向我显示如下序列:

What I want is a transition matrix which shows me the sequence like:

• 一个 1 后面跟着一个 1 的频率
• 一个 1 后面跟着一个 2 的频率

• 一个 1 后面跟着一个 3 的频率

• How often is a 1 followed by a 1
• How often is a 1 followed by a 2

• How often is a 1 followed by a 3

一个 2 后面跟着一个 1 的频率

How often is a 2 followed by a 1

等等...

((0,2,1), (1,2,1), (2,0,0))

((0,2,1), (1,2,1), (2,0,0))

有没有预制模块去拿这个?

Is there a premade module go get this?

推荐答案

我不知道是否有模块，但我会使用这段代码，它很容易推广:

I don't know if there's a module, but I'd go with this code, which is easily generalizeable:

import numpy as np
from collections import Counter
a = [2, 1, 3, 1, 2, 3, 1, 2, 2, 2]
b = np.zeros((3,3))
for (x,y), c in Counter(zip(a, a[1:])).iteritems():
    b[x-1,y-1] = c
print b
array([[ 0.,  2.,  1.],
       [ 1.,  2.,  1.],
       [ 2.,  0.,  0.]])

没有安装numpy:

b = [[0 for _ in xrange(3)] for _ in xrange(3)]
for (x,y), c in Counter(zip(a, a[1:])).iteritems():
    b[x-1][y-1] = c

print b
[[0, 2, 1], [1, 2, 1], [2, 0, 0]]

如果需要，一些正在发生的事情的细节:

A few details of what's going on, if needed:

1. zip(a, a[1:]) 获取所有连续数字对.
2. Counter 计算每对出现的次数
3. for 循环简单地将Counter 生成的字典转换为您请求的矩阵/列表列表

1. zip(a, a[1:]) gets all the pairs of consecutive numbers.
2. Counter counts how many times each pair appears
3. The for loop simple converts the dictionary Counter produces into the matrix / list of lists you requested

这篇关于Python 转换矩阵的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！