在循环中，将项目与数据框列中的值匹配，然后将单独的列值存储为变量

Question

我有一个现有循环，用于遍历大量文件路径，最终通过云处理管道发送文件。我需要更新循环以将文件名与数据框列 (fileName) 匹配，然后从第二列 (date) 获取关联的数据值并将其作为变量存储在我的循环中。

# dataframe that I need to extract 'date' from
df = pd.DataFrame({'id':['dat1', 'dat2', 'dat3'],
        'date':[2019, 2021, 2015],
        'fileName': ['dat1.file', 'dat2.file', 'dat3.file']})


# list of file paths that I need the fileName from to match with my dataframe
gs_files = ['path/dat1.file', 'path/dat2.file']
bucket = 'path/'


for f in gs_files:
    # get file path
    print('Path: ', f)

    # get file name (need to keep this for later processing steps)
    fbname = f.replace(bucket, '')
    print('Image name: ', fbname)

    # match fbname with df['fileName']. Store associated 'date' as a separate variable (not as a column in df)
    if fbname in df['fileName']:
        year = df['date']
        print('Collection date: ',year)

    # Extra processing steps will be executed below.

# Resulting output from the above code:
Path:  path/dat1.file
Image name:  dat1.file
Path:  path/dat2.file
Image name:  dat2.file

# Desired output:
Path:  path/dat1.file
Image name:  dat1.file
Collection date: 2019

Path:  path/dat2.file
Image name:  dat2.file
Collection date: 2021

Answer 1

更改此代码：

if fbname in df['fileName']:
    year = df['date']
    print('Collection date: ',year)

到这里：

if df['fileName'].isin([fbname]).any():
    year = df['date'][df['fileName'] == fbname].iloc[0]
    print('Collection date: ',year)

fbname in df['fileName'] 不起作用。相反，df['fileName'].isin([fbname]) 将为您指定的列表 ([fbname]) 中的原始列中的每个项目返回一个包含 True 的新列，否则为 False。然后，.any() 返回 True 如果在调用它的列中至少有一个 True。

另外，df['date'][df['fileName'] == fbname] 从date 中选择项目，其中fileName 是fbname。 .iloc[0] 获取实际值。