替换Python字典中的值 [英] Replace values in Python dict

问题描述

我有2个文件，第一只有2个文件列

I have 2 files, The first only has 2 columns

A   2
B   5
C   6

第二将字母作为第一列.

And the second has the letters as a first column.

A  cat
B  dog
C  house

我想用与第一个文件相对应的数字替换第二个文件中的字母，以便获取.

I want to replace the letters in the second file with the numbers that correspond to them in the first file so I would get.

2  cat
5  dog
6  house

我从第一个字典创建了一个字典，然后阅读了第二个字典.我尝试了一些尝试，但没有任何效果.我似乎无法替换这些值.

I created a dict from the first and read the second. I tried a few things but none worked. I can't seem to replace the values.

import csv
with open('filea.txt','rU') as f:
    reader = csv.reader(f, delimiter="\t")
    for i in reader:
        print i[0]  #reads only first column
        a_data = (i[0])


dictList = []
with open('file2.txt', 'r') as d:
        for line in d:
            elements = line.rstrip().split("\t")[0:]
            dictList.append(dict(zip(elements[::1], elements[0::1])))

for key, value in dictList.items():
            if value == "A":
                    dictList[key] = "cat"

推荐答案

问题似乎出在您的最后几行:

The issue appears to be on your last lines:

for key, value in dictList.items():
    if value == "A":
        dictList[key] = "cat"

这应该是:

for key, value in dictList.items():
    if key in a_data:
        dictList[a_data[key]] = dictList[key]
        del dictList[key]

d1 = {'A': 2, 'B': 5, 'C': 6}
d2 = {'A': 'cat', 'B': 'dog', 'C': 'house', 'D': 'car'}

for key, value in d2.items():
    if key in d1:
        d2[d1[key]] = d2[key]
        del d2[key]

>>> d2
{2: 'cat', 5: 'dog', 6: 'house', 'D': 'car'}

请注意，此方法允许第二个字典中的项没有第一个字典中的键.

Notice that this method allows for items in the second dictionary which don't have a key from the first dictionary.

以条件字典理解格式包装:

Wrapped up in a conditional dictionary comprehension format:

>>> {d1[k] if  k in d1 else k: d2[k] for k in d2}
{2: 'cat', 5: 'dog', 6: 'house', 'D': 'car'}

我相信这段代码可以为您带来理想的结果:

I believe this code will get you your desired result:

with open('filea.txt', 'rU') as f:
    reader = csv.reader(f, delimiter="\t")
    d1 = {}
    for line in reader:
        if line[1] != "":
            d1[line[0]] = int(line[1])

with open('fileb.txt', 'rU') as f:
    reader = csv.reader(f, delimiter="\t")
    reader.next()  # Skip header row.
    d2 = {}
    for line in reader:
        d2[line[0]] = [float(i) for i in line[1:]]

d3 = {d1[k] if k in d1 else k: d2[k] for k in d2}

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