假设文本文件包含以下元素：
    A
    B
    C
    D 
我想使用Python将这些元素写入CSV文件，如下所示：
    A,A
    A,B
    A,C
    A,D
    B,A
    B,B
    B,C
    B,D
    ...
我尝试使用以下代码将文本写入带有复制数据的CSV中：
```python
import csv
with open(r'C:\Users\soso-\Desktop\SVM\DataSet\drug_list.txt') as f:
    with open('integrated_x.csv', 'w') as out_file:
        for line in f:
            for x in range(548):
                out_file.write(f"{line.strip()}\n")
f.close()
out_file.close()

A
A
A
A
B
B
B
...

with open(r'C:\Users\soso-\Desktop\SVM\DataSet\drug_list.txt') as f:
    with open(r'integrated_x.csv') as read_obj, \
            open('integrated_x12.csv', 'w', newline='') as write_obj:
        # 从输入文件对象创建csv.reader对象
        csv_reader = csv.reader(read_obj)
        # 从输出文件对象创建csv.writer对象
        csv_writer = csv.writer(write_obj)
        # 将输入csv文件的每一行读取为列表
        for row in csv_reader:
            for line in f:
                # 将默认文本附加到行/列表中
                row.append(line.strip())
                # 将更新后的行/列表添加到输出文件
                csv_writer.writerow(row)

A,"A"
A,"A,B"
A,"A,B,C"

<details>
<summary>英文:</summary>
suppose the text file contain these elements as follows:
    A
    B
    C
    D 
I want to write these elements in the CSV file using python as follows:
    A,A
    A,B
    A,C
    A,D
    B,A
    B,B
    B,C
    B,D
    ...
I try to write the text in csv with multiplicated data like this:
    import csv
    
    with open(r&#39;C:\Users\soso-\Desktop\SVM\DataSet\drug_list.txt&#39;) as f:
        with open(&#39;integrated_x.csv&#39;, &#39;w&#39;) as out_file:
            for line in f:
                for x in range(548):
                    out_file.write(f&quot;{line.strip()}\n&quot;)
    f.close()
    out_file.close()
output:
    A
    A
    A
    A
    B
    B
    B
    ....
Then add the new column for the csv file in the other csv file like this:
    with open(r&#39;C:\Users\soso-\Desktop\SVM\DataSet\drug_list.txt&#39;) as f:
        with open(r&#39;integrated_x.csv&#39;) as read_obj, \
                open(&#39;integrated_x12.csv&#39;, &#39;w&#39;, newline=&#39;&#39;) as write_obj:
        # Create a csv.reader object from the input file object
                    csv_reader = csv.reader(read_obj)
        # Create a csv.writer object from the output file object
                    csv_writer = csv.writer(write_obj)
            
        # Read each row of the input csv file as list
                    for row in csv_reader:
                        for line in f:
            # Append the default text in the row / list
                            row.append(line)
            # Add the updated row / list to the output file
                            csv_writer.writerow(row)
output:
    A,&quot;A&quot;
    A,&quot;A,B&quot;
    A,&quot;A,B,C&quot;
So the output not as expected it append the column as list and replicate the previous row.
How can I fix it?
</details>
# 答案1
**得分**: 0
使用标准库中的itertools.permutations：
```python
import itertools
list(itertools.permutations(['A', 'B', 'C', 'D'], 2))

import pandas as pd
import itertools
a = list(itertools.permutations(['A', 'B', 'C', 'D'], 2))
df = pd.DataFrame(list(itertools.permutations(['A', 'B', 'C', 'D'], 2)))
df.to_csv('my_file.csv')