Python 3.x 生成数据帧的函数返回None

首先,

我创建了一个函数，在这个函数中，我将一些标题值转换为一列，然后保留每个标题的值。更具体地说，我的文件之前和之后如下所示：

代码是：

#Transpose function

def transpose(df):

    #Create a list of all the columns
    columns = list(df)
    
    #Create lists to hold headers and sites
    headers = []
    sites = []
    
    #Split columns list into headers and sites
    for col in columns:
        if col.startswith('Date') or col.startswith('Metric'):
            headers.append(col)
        else:
            sites.append(col)
    
    #Finalise the transpose of the headers into a new column using a new dataframe
    df = pd.melt(df,
                      id_vars=headers,
                      value_vars=sites,
                      var_name='Site',
                      value_name='Value')

我现在尝试对多个文件使用此函数。我在一个路径中有文件夹，每个文件夹都有第一张图片所示格式的文件。为了使这个过程自动化，我的想法是创建一个包含数据帧的字典，然后将这些帧合并成一个。如果我在for循环中添加函数代码，效果很好：

#Dictionary of parent folders 
dictionary = {}
#Dictionary of dataframes/ files per folder
dataframe_dictionary = {}
#list of all data frames. This is going to be used to create a final output (concat dataframes)
all_dataframes = []

#Find all subfolders in path
folderpath = r'C:\Documents\\'
onlyfolders = [f for f in listdir(folderpath) if not isfile(join(folderpath, f))]

#Find all the files for each folder and create a dictionary (Parent folder and its files)
for i in onlyfolders:
    path = folderpath+i
    pathfiles = [f for f in listdir(path) if isfile(join(path, f))]
    dictionary[i] = pathfiles
    numberOfFiles = len(dictionary[i])

#For each folder (folder) and then for each file create dataframe based on each CSV
for folder, file in dictionary.items():
    for x in file:
        #Create a unique dataframe per folder and file 
        filename = r'C:\Documents\\'+folder+'\\'+x
        dataframe_dictionary[folder+'_'+x.replace(".csv", "")] = pd.read_csv(filename,skiprows=6,sep=',')
        clean_name = dataframe_dictionary[folder+'_'+x.replace(".csv", "")]
        clean_name['Folder'] = folder
        ####COPY PASTE THE CODE OF THE FUNCTION WITHOUT CALLING IT
        all_dataframes.append(clean_name)

#Export final output
final_output = pd.concat(all_dataframes)
final_output.to_csv(r'DF1.csv', index = False)

但如果我尝试使用此选项，它将返回一个错误：

final_dataframe = transpose(clean_name)

错误是：

传递的所有对象均为“无”

---

问题是函数返回None。除此之外，对于如何使代码更高效、更好（不同的方法）还有什么建议吗？

我看不出您在代码中在哪里使用了

转置功能！，你把它叫做哪里。。而且
转置
功能运行良好，我刚刚测试过。如果不是empy，请检查
clean_name
。