从多个 csv 文件中提取所有特定行（单独）并组合行以另存为新文件

Question

I have a number of csv files. I need to extract all respective rows from each file and save it as a new file. ie first output file must contain first rows of all input files and so on.

I have done the following.

import pandas as pd
import os
import numpy as np
data = pd.DataFrame('', columns =['ObjectID', 'SPI'], index = np.arange(1,100))
path = r'C:\Users\bikra\Desktop\Pandas'
i = 1
for files in os.listdir(path):
    if files[-4:] == '.csv': 
        for j in range(0,10, 1):
        #print(files) 
            dataset = pd.read_csv(r'C:\Users\bikra\Desktop\Pandas'+'\\'+files)
            spi1 = dataset.loc[j,'SPI'] 
            data.loc[i]['ObjectID'] = files[:]
            data.loc[i]['SPI'] = spi1
            data.to_csv(r'C:\Users\bikra\Desktop\Pandas\output\\'+str(j)+'.csv') 
            i + 1

It works well when index (ie 'j' ) is specified. But when I tried to loop, the output csv file contains only first row. Where am I wrong?

Answer 1

You better use append:

data = data.append(spi1)