Python循环将数据保存到文件/全局变量

Question

I have two for loops in which I call the forecast function. The function returns the forecast value and I want to write it to a file or in a dataframe such that I can save all the predictions and access them outside the loop scope. I am a little stuck here. let me show by example.

 for country in df['country'].unique():
      for channel in df['channel'].unique():
          output = pd.DataFrame(columns=['date', 'country', 
                                          'channel_id','value'])
          x = df[df['country']==country & df['channel']==channel]
          pred = forecast(df)
          output = output.append(pred)
          output.to_csv('forecast.csv')

This is what I want to do but the problem is, well obvious, the data is lost after each iteration. Please suggest a way to keep it.

Answer 1

To delimit by a tab you can use the sep argument of to_csv:

output.to_csv(file_name, sep='\\t')

To use a specific encoding (eg 'utf-8') use the encoding argument:

output.to_csv(file_name, sep='\\t', encoding='utf-8')