用逗號分隔值分割csv中的行

我有 csv 檔案，列中的資訊（id 和文本）如下例所示：

1, ?ildomos grindys
2, ?ildomos grindys, Rekuperacin? sistema
3, 
4, Skalbimo ma?ina, Su baldais, ?aldytuvas, ?ildomos grindys

我想要的輸出是將 ID 傳輸到一行并將其與其文本相關聯（它用于資料庫）。由于 csv 檔案真的很大，我只給你一小部分來理解我想要什么：

| ID             | Features   
 ---------------- -------------
| 1              | ?ildomos grindys
| 2              | ?ildomos grindys
| 2              | Rekuperacin? sistema
| 3              | null
| 4              | Skalbimo ma?ina
| 4              | Su baldais
| 4              | ?aldytuvas
| 4              | ?ildomos grindys

我怎么能通過 python 做到這一點？謝謝 ！

uj5u.com熱心網友回復：

這是一種執行您所要求的方法：

with open('infoo.txt', 'r', encoding="utf-8") as f:
    records = []
    rows = [[x.strip() for x in row.split(',')] for row in f.readlines()]
    for row in rows:
        for i in range(1, len(row)):
            records.append([row[0], row[i] if row[i] else 'null'])
    with open('outfoo.txt', 'w', encoding="utf-8") as g:
        g.write('ID,Features\n')
        for record in records:
            g.write(f'{",".join(field for field in record)}\n')

# check the output file:
with open('outfoo.txt', 'r', encoding="utf-8") as f:
    print('contents of output file:')
    [print(row.strip('\n')) for row in f.readlines()]

輸出：

contents of output file:
ID,Features
1,?ildomos grindys
2,?ildomos grindys
2,Rekuperacin? sistema
3,null
4,Skalbimo ma?ina
4,Su baldais
4,?aldytuvas
4,?ildomos grindys

更新：

另一種方法是使用 pandas ( docs )。Pandas 提供了許多強大的方法來處理表格資料，但它也有一些學習曲線：

import pandas as pd
with open('infoo.txt', 'r', encoding="utf-8") as f:
    records = []
    rows = [[x.strip() for x in row.split(',')] for row in f.readlines()]
    df = pd.DataFrame([[row[0], row[1:]] for row in rows], columns=['ID', 'Feature'])
    print('Dataframe read from input file:'); print(df)
    df = df.explode('Feature').reset_index(drop=True)
    print('Dataframe with one Feature per row:'); print(df)
    df.to_csv('outfoo.txt', index = False)

    # check the output file:
    df2 = pd.read_csv('outfoo.txt')
    print('Dataframe re-read from output file:'); print(df2)

輸出

Dataframe read from input file:
  ID                                            Feature
0  1                                 [?ildomos grindys]
1  2           [?ildomos grindys, Rekuperacin? sistema]
2  3                                                 []
3  4  [Skalbimo ma?ina, Su baldais, ?aldytuvas, ?ild...
Dataframe with one Feature per row:
  ID               Feature
0  1      ?ildomos grindys
1  2      ?ildomos grindys
2  2  Rekuperacin? sistema
3  3
4  4       Skalbimo ma?ina
5  4            Su baldais
6  4            ?aldytuvas
7  4      ?ildomos grindys
Dataframe re-read from output file:
   ID               Feature
0   1      ?ildomos grindys
1   2      ?ildomos grindys
2   2  Rekuperacin? sistema
3   3                   NaN
4   4       Skalbimo ma?ina
5   4            Su baldais
6   4            ?aldytuvas
7   4      ?ildomos grindys

熊貓檔案的鏈接在這里：

• 資料框
• 爆炸
• to_csv
• read_csv

uj5u.com熱心網友回復：

您可以閱讀 CSV，然后將每一行附加到一個新串列中。

data.csv：

1, ?ildomos grindys
2, ?ildomos grindys, Rekuperacin? sistema
3,
4, Skalbimo ma?ina, Su baldais, ?aldytuvas, ?ildomos grindys

代碼：

import csv

data = []
with open('data.csv') as csvfile:
    reader = csv.reader(csvfile)
    for row in reader:
        for i in range(1, len(row)):
            value = row[i].strip()
            if value == "":
                value = "null"
            data.append([int(row[0]), value])
print(data)

輸出：

[[1, '?ildomos grindys'], [2, '?ildomos grindys'], [2, 'Rekuperacin? sistema'], [3, 'null'], [4, 'Skalbimo ma?ina'], [4, 'Su baldais'], [4, '?aldytuvas'], [4, '?ildomos grindys']]

參考：

• CSV 模塊上的 Python 檔案

標籤：Python CSV

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