使用python脚本从csv文件中删除重复的行

Question

目标

我从hotmail下载了一个CSV文件,但它有很多重复项.这些副本是完整的副本,我不知道为什么我的手机创建它们.

我想摆脱重复.

途径

编写一个python脚本来删除重复项.

技术规格

Windows XP SP 3
Python 2.7
CSV file with 400 contacts

Answer 1

更新:2016年

如果您乐意使用有用的more_itertools外部库:

from more_itertools import unique_everseen
with open('1.csv','r') as f, open('2.csv','w') as out_file:
    out_file.writelines(unique_everseen(f))

@ IcyFlame解决方案的更高效版本

with open('1.csv','r') as in_file, open('2.csv','w') as out_file:
    seen = set() # set for fast O(1) amortized lookup
    for line in in_file:
        if line in seen: continue # skip duplicate

        seen.add(line)
        out_file.write(line)

要就地编辑同一个文件,您可以使用它

import fileinput
seen = set() # set for fast O(1) amortized lookup
for line in fileinput.FileInput('1.csv', inplace=1):
    if line in seen: continue # skip duplicate

    seen.add(line)
    print line, # standard output is now redirected to the file

Answer 2

您可以使用Pandas有效地实现重复数据删除:

import pandas as pd
file_name = "my_file_with_dupes.csv"
file_name_output = "my_file_without_dupes.csv"

df = pd.read_csv(file_name, sep="\t or ,")

# Notes:
# - the `subset=None` means that every column is used 
#    to determine if two rows are different; to change that specify
#    the columns as an array
# - the `inplace=True` means that the data structure is changed and
#   the duplicate rows are gone  
df.drop_duplicates(subset=None, inplace=True)

# Write the results to a different file
df.to_csv(file_name_output)

Answer 3

您可以使用以下脚本:

前提:

1. 1.csv 是包含重复项的文件
2. 2.csv 是执行此脚本后将缺少重复项的输出文件.

码

inFile = open('1.csv','r')

outFile = open('2.csv','w')

listLines = []

for line in inFile:

    if line in listLines:
        continue

    else:
        outFile.write(line)
        listLines.append(line)

outFile.close()

inFile.close()

算法解释

在这里,我正在做的是:

1. 在读取模式下打开文件.这是具有重复项的文件.
2. 然后在一个循环中运行直到文件结束,我们检查该行是否已经遇到过.
3. 如果遇到过,我们不会将其写入输出文件.
4. 如果不是,我们会将其写入输出文件并将其添加到已经遇到的记录列表中