Python添加了帶有標題的新列

Question

我想在現有文件中添加一個新列，並且希望將輸出寫入另一個文件。我打開文件如下，並添加我所需的語句。如何通過在最後添加新列（使用列名稱/標題）將輸出寫入文件。分離是標籤。輸入的

with open(newfile, 'w') as outfile: 
    with open(oldfile, 'r', encoding='utf-8') as infile: 
     statements: 

樣品：

Col1 Col2 Col3 Col4 

Val1 Val1 Val1 Val1 
Val2 Val2 Val2 Val2 
Val3 Val3 Val3 Val3 
Val4 Val4 Val4 Val4 

輸出的樣品：

Col1 Col2 Col3 Col4 Col5(Newly added) 

Val1 Val1 Val1 Val1 Val1 
Val2 Val2 Val2 Val2 Val2 
Val3 Val3 Val3 Val3 Val3 
Val4 Val4 Val4 Val4 Val4 

預先感謝。

Answer 1

import csv 

with open('data','r') as f_in: 
    with open('data_out', 'w') as f_out: 
     writer = csv.writer(f_out, delimiter=' ', lineterminator='\n') 
     reader = csv.reader(f_in, delimiter=' ') 

     result = [] 
     # read headers 
     row = next(reader) 
     # add new header to list of headers 
     row.append('Col5') 
     result.append(row) 

     for row in reader: 
      # add new column values 
      row.append(row[0]) 
      result.append(row) 

     writer.writerows(result) 

data_out 

Col1 Col2 Col3 Col4 Col5 
Val1 Val1 Val1 Val1 Val1 
Val2 Val2 Val2 Val2 Val2 
Val3 Val3 Val3 Val3 Val3 
Val4 Val4 Val4 Val4 Val4 

Answer 2

假設您事先知道新列的名稱，您可以編寫以下代碼，如果情況並非如此，您可以在for循環中的first_line條件下計算它。如果您需要其他行爲，只需在for循環中更改else部分即可。如果您需要其他行爲，請在for循環中更改else部分。

new_column_name = 'Col5' 
with open(newfile, 'w') as outfile: 
    with open(oldfile, 'r', encoding='utf-8') as infile: 
     for line in infile: 
      if first_line: 
       outfile.write('{} {}\n'.format(line, new_column_name)) 
       first_line = False 
      else: 
       values = line.split() 
       if values: 
        values.append(values[-1]) 
       outfile.write(' '.join(values) + '\n') 

希望它能幫助，