Question

我尝试将多个CSV文件合并为一个用于我的数据集的大CSV。我正在寻找的是从多个CVS文件中获取少量列数据并从中生成数据集。我不想要我最终数据集中的所有列，但很少有选定的列。我在读取CSV时已经在熊猫中使用了names属性并且它返回正常但我无法从获取的CSV中创建新的CSV。我在这里做错了什么？我在底部添加了堆栈跟踪。

import glob
import pandas as pd
import os
import time
from datetime import datetime
import numpy as np

path = "C:\Users\lenovo\Downloads\Compressed\LoanStats3a.csv_2\csv"
class MergeCsvFiles:
def MergeCsv(self):
    allFiles = glob.glob(os.path.join(path, "LoanStats3a.csv"))
    print 'allFiles',allFiles

    for file_ in allFiles:
        print 'file_ ######### ',file_

        # merge_df = pd.DataFrame.from_csv(file_)
        # print merge_df
        fileToSave = glob.glob(os.path.join(path, "merge.csv"))
        print 'filrToSave #### ', fileToSave
        np_array_list = []

        df = pd.read_csv(file_, skipinitialspace=True,low_memory=False,header=0,index_col=None)
        np_array_list.append(df.as_matrix())
        comb_np_array = np.vstack(np_array_list)
        big_frame = pd.DataFrame(comb_np_array)
        # big_frame.columns = fields
        print 'big_frame#### ', big_frame
        big_frame.to_csv(fileToSave)

        # See the keys
        print 'df.keys########',df.keys()
        print 'df @@@@@', df
        frame = pd.DataFrame()
        list_ = []

        list_.append(df)
        frame = pd.concat(list_)
        # print 'frame#### ',frame

        frame.to_csv(fileToSave)

if __name__ == "__main__":
    s =  MergeCsvFiles()
    s.MergeCsv()

StackTrace：

Traceback (most recent call last):
  File "C:/Users/lenovo/Downloads/Video/Machine Learning/MLPredictiveAnalysis/MergeCsv.py", line 59, in <module>
    s.MergeCsv()
  File "C:/Users/lenovo/Downloads/Video/Machine Learning/MLPredictiveAnalysis/MergeCsv.py", line 39, in MergeCsv
    big_frame.to_csv(fileToSave)
  File "C:\Python27\lib\site-packages\pandas\core\frame.py", line 1344, in to_csv
    formatter.save()
  File "C:\Python27\lib\site-packages\pandas\formats\format.py", line 1526, in save
    compression=self.compression)
  File "C:\Python27\lib\site-packages\pandas\io\common.py", line 426, in _get_handle
    f = open(path, mode)
TypeError: coercing to Unicode: need string or buffer, list found

Answer 1

glob.glob返回一个列表。您需要将路径名的字符串传递给big_frame.csv。为什么你甚至需要全球？ big_frame.csv(os.path.join(path, "merge.csv"))应该有用。

您也在循环底部用frame.to_csv(fileToSave)编写此文件。每次迭代都会写入文件，因此只有最后一次迭代才能保存任何文件。

Panda to_csv（）：TypeError：强制转换为Unicode：需要字符串或缓冲区，找到列表

1 个答案: