Python脚本将输入的csv列转换为输出的csv行值

Question

我有一个看起来像的输入csv

email,trait1,trait2,trait3
foo@gmail,biz,baz,buzz
bar@gmail,bizzy,bazzy,buzzy
foobars@gmail,bizziest,bazziest,buzziest

我需要输出格式看起来像

Indv,AttrName,AttrValue,Start,End
foo@gmail,"trait1",biz,,,
foo@gmail,"trait2",baz,baz,,
foo@gmail,"trait3",buzz,,,

对于输入文件中的每一行，我需要为输入csv中的N-1列写一行。 在某些情况下，输出文件中的“开始”和“结束”字段可以为空。

我正在尝试使用DictReader读取数据。 所以因为我已经能够用

import unicodecsv
import os
import codecs

with open('test.csv') as csvfile:
    reader = unicodecsv.csv.DictReader(csvfile)
    outfile = codecs.open("test-write", "w", "utf-8")
    outfile.write("Indv", "ATTR", "Value", "Start","End\n")
    for row in reader:
        outfile.write([row['email'],"trait1",row['trait1'],'',''])
        outfile.write([row['email'],"trait2",row['trait2'],row['trait2'],''])
        outfile.write([row['email'],"trait3",row['trait3'],'','')

这不起作用。 （我认为我需要将列表转换为字符串），并且在我对每一行的列名进行硬编码时也非常脆弱。 更大的问题是for循环中的数据未写入"test-write" 。 outfile.write("Indv", "ATTR", "Value", "Start","End\\n")只有outfile.write("Indv", "ATTR", "Value", "Start","End\\n")实际写入文件。 DictReader是适合我的情况的类吗？

Answer 1

这使用了unicodecsv.DictWriter和zip()函数来执行您想要的操作，并且我认为代码相当可读。

import unicodecsv
import os
import codecs

with open('test.csv') as infile, \
     codecs.open('test-write.csv', 'w', 'utf-8') as outfile:

    reader = unicodecsv.DictReader(infile)
    fieldnames = 'Indv,AttrName,AttrValue,Start,End'.split(',')
    writer = unicodecsv.DictWriter(outfile, fieldnames)
    writer.writeheader()
    for row in reader:
        email = row['email']
        trait1, trait2, trait3 = row['trait1'], row['trait2'], row['trait3']
        writer.writerows([  # writes three rows of output from each row of input
            dict(zip(fieldnames, [email, 'trait1', trait1])),
            dict(zip(fieldnames, [email, 'trait2', trait2, trait2])),
            dict(zip(fieldnames, [email, 'trait3', trait3]))])

这是从示例输入csv文件生成的test-write.csv文件的内容：

Indv,AttrName,AttrValue,Start,End
foo@gmail,trait1,biz,,
foo@gmail,trait2,baz,baz,
foo@gmail,trait3,buzz,,
bar@gmail,trait1,bizzy,,
bar@gmail,trait2,bazzy,bazzy,
bar@gmail,trait3,buzzy,,
foobars@gmail,trait1,bizziest,,
foobars@gmail,trait2,bazziest,bazziest,
foobars@gmail,trait3,buzziest,,

Answer 2

由于我不会对Unicode进行大量工作，因此我可能会完全不满意，但在我看来，以下方法应该可以工作：

import csv

with open('test.csv', 'ur') as csvin, open('test-write', 'uw') as csvout:
    reader = csv.DictReader(csvin)
    writer = csv.DictWriter(csvout, fieldnames=['Indv', 'AttrName', 
                                                'AttrValue', 'Start', 'End'])
    for row in reader:
        for traitnum in range(1, 4):
            key = "trait{}".format(traitnum)
            writer.writerow({'Indv': row['email'], 'AttrName': key,
                             'AttrValue': row[key]})

Answer 3

import pandas as pd
pd1 = pd.read_csv('input_csv.csv')
pd2 = pd.melt(pd1, id_vars=['email'], value_vars=['trait1','trait2','trait3'], var_name='AttrName', value_name='AttrValue').rename(columns={'email': 'Indv'}).sort(columns=['Indv','AttrName']).reset_index(drop=True)
pd2.to_csv('output_csv.csv', index=False)

不清楚“ Start和“ End字段代表什么，但这可以给您带来其他好处。