python - 连续处理 .csv 文件并在特定列包含非空单元格时提取行

Question

我正在开发一个代码，用于在 for 循环中处理多个 .csv 文件，然后仅提取(到新的 .csv 文件中)与名为“20210-2.0”的特定列中的非空字符串单元格匹配的行。非空字符串单元格的名称相同(即 20210-2.0)。以下是显示 csv 文件部分内容的屏幕截图:

https://uoe-my.sharepoint.com/:i:/g/personal/gpapanas_ed_ac_uk/EayBblFTHmVJvRfsB6h8Vr4B09IfjQ2L1I5OQKUN2p5wzw?e=2gXW61

import pandas as pd
import glob
import os

path = './'

all_files = glob.glob(path + "/*.csv")

li = []

for filename in all_files:

    df = pd.read_csv(filename, index_col=None)
    li.append(df)
    df = li[li['20201-2.0'].notnull()]

    print('extracting info from cvs...')
    print(df)

    # You can now export all outcomes in new csv files
    file_name = filename + 'new' + '.csv'
    save_path = os.path.abspath(
        os.path.join(
            path, file_name
        )
    )
    print('saving ...')
    export_csv = df.to_csv(save_path, index=None)

我收到以下错误:

df = li[li['20201-2.0'].notnull()]
TypeError: list indices must be integers or slices, not str

Answer 1

在循环内，读取文件后，自动过滤它，然后将其存储在列表中。

df = pd.read_csv(filename, index_col=None, header = 0)    # You read the file in your directory under the variable filename, but it needs to know that you have a column header. Your '20201-2.0' value is a column name right?
df = df[df['20201-2.0'].notnull()]                        # You now get a new dataframe from the one you load, but now you only got the rows in which the column named '20201-2.0' has been populated.
li.append(df)                                             # Store that dataframe in a list called `li`

我还注意到，在保存为新的 csv 文件时，您在每个 filname 中添加了 "new" 字符串和 ".csv" 字符串 你拥有的字符串变量。

你运行过这段代码吗？它不会将您的文件保存为“something.csvnew.csv”吗？