如何使用Python将一个CSV文件拆分成多个文件

Question

我有一个CSV文件（world.csv），长这样：

"city","city_alt","lat","lng","country"
"Mjekić","42.6781","20.9728","Kosovo"
"Mjekiff","42.6781","20.9728","Kosovo"
"paris","42.6781","10.9728","France"
"Bordeau","16.6781","52.9728","France"
"Menes","02.6781","50.9728","Morocco"
"Fess","6.6781","3.9728","Morocco"
"Tanger","8.6781","5.9728","Morocco"

我希望将其按国家拆分为多个文件，如下所示：

Kosovo.csv:

"city","city_alt","lat","lng","country"
"Mjekić","42.6781","20.9728","Kosovo"
"Mjekiff","42.6781","20.9728","Kosovo"

France.csv：

"city","city_alt","lat","lng","country"
"paris","42.6781","10.9728","France"
"Bordeau","16.6781","52.9728","France"

摩洛哥.csv：

"city","city_alt","lat","lng","country"
"Menes","02.6781","50.9728","Morocco"
"Fess","6.6781","3.9728","Morocco"
"Tanger","8.6781","5.9728","Morocco"

- FlutterLover

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将CSV文件按列数据拆分成多个文件：这将有助于。 - deadshot

加载到 pandas.DataFrame 中，然后您可以轻松选择行并仅保存所选行。 - furas

Answer 1

尝试以下操作：

根据国家名称筛选列。然后使用 pandas 中的 to_csv 将其转换为 CSV 文件。

df = pd.read_csv('test.csv')

france = df[df['country']=='France']
kosovo = df[df['country']=='Kosovo']
morocco = df[df['country']=='Morocco']

france.to_csv('france.csv', index=False)
kosovo.to_csv('kosovo.csv', index=False)
morocco.to_csv('morocco.csv', index=False)

- deadshot

Answer 2

如果您无法使用 pandas，可以使用内置的 csv 模块和 itertools.groupby() 函数。您可以使用它来按国家进行分组。

from itertools import groupby
import csv

with open('world.csv') as csv_file:
    reader = csv.reader(csv_file)
    next(reader) #skip header
    
    #Group by column (country)
    lst = sorted(reader, key=lambda x : x[4])
    groups = groupby(lst, key=lambda x : x[4])

    #Write file for each country
    for k,g in groups:
        filename = k + '.csv'
        with open(filename, 'w', newline='') as fout:
            csv_output = csv.writer(fout)
            csv_output.writerow(["city","city_alt","lat","lng","country"])  #header
            for line in g:
                csv_output.writerow(line)

- jignatius

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它给了我很多相同国家的CSV文件。 - FlutterLover

我需要为每个国家一个CSV文件。 - FlutterLover

@FlutterLover 使用你的world.csv文件，我得到了三个文件：Morocco.csv、Kosovo.csv和France.csv。这不是你想要的吗？你得到了哪些文件？ - jignatius

@FlutterLover 我刚刚注意到你的world.csv文件似乎缺少一列。标题中有五个列名，但实际数据中只有四列。也许这是一个复制粘贴错误？如果数据包含五列，请尝试在我的代码中将x [3]更改为x [4]。 - jignatius

是的，现在可以工作了，只需将x[3]更改为x[4]。非常感谢。 - FlutterLover

@FlutterLover 很棒！ - jignatius

Answer 3

最简单的方法如下： #在您的工作目录中创建一个名为“adata”的文件夹 #导入glob模块

for i,g in df.groupby('CITY'):
    g.to_csv('adata\{}.csv'.format(i), header=True, index_label='Index')
print(glob.glob('adata\*.csv'))
filenames = sorted(glob.glob('adata\*.csv'))

for f in filenames:
    #your intended processes

- Saikat