解决方法：在这种情况下，“ ValueError：无法设置没有定义索引和标量的框架”

Question

我正在尝试从“印度国家GDP数据文件”中选择两个特定的对象，转置数据集（以创建行），并将所有文件中的这些行连接起来以创建新的数据框。我收到此错误。请告诉我如何解决此问题。

import pandas as pd
import numpy as np
import glob
path = r'D:\Data Science\assignment\GDP Assignment\Data IB'
all_files = glob.glob(path+'/*.csv')

li = []
for filename in all_files:
    df = pd.read_csv(filename, index_col = None, header = 0)
    df = df[['Item','2014-15']]
    df = df.set_index('Item')
    df = df.T
    # Taking the header row
    new_header = df.iloc[0] #grab the first row for the header
    df = df[1:] #take the data less the header row 
    # Assign the new header
    df.columns = new_header 
    # Add the section name from the filename
    df.loc[:,'States'] = filename.split('\\')[-1].split('.')[0].lstrip('NAD').lstrip('-')
    li.append(df)
# Creating a final DF by joining all the df's in the list li
frame = pd.concat(li, axis=0, ignore_index=True)