读取多个文件后，Pandas数据框合并为一个

Question

我正在读取多个文件（相同的标题，列等）并执行一些预处理。如何将“ for”循环的输出合并到一个单独的DataFrame中？我尝试使用data.append（df），但它也包含标题列，并将其变成列表，而不是保持数据帧格式

dir = 'C:/PythonProjects/PAMAP2_Dataset/Protocol/'
filelist = ['subject101.dat','subject102.dat','subject103.dat','subject104.dat','subject105.dat','subject106.dat','subject107.dat']
columns = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,20,21,22,23,24,25,26,27,28,29,30,31,32,37,38,39,40,41,42,43,44,45,46,47,48,49]
ID_rows = [3,4,12,13]
data=[]
for file in filelist:
    input = dir + file
    df = pd.read_csv(input, header=None, delim_whitespace=True)
    print('Done reading data file ', input)
    df = df[columns]
    df = df[df[1].isin(ID_rows)]
    df=df.fillna(0)
    df = (df - df.mean()) / df.std()
    #print(df)
    data.append(df)
    #print(data)