How can I convert .append to .concat panda python-CodePudding

I have a current iteration to fill new rows to a dataframe based on new series created:

    current = self.getAllCandles(self.active_id,start_candle)
    main = pd.DataFrame()
    useful_frame = pd.DataFrame()
    for candle in current:
        useful_frame = pd.DataFrame(list(candle.values()),index = list(candle.keys())).T.drop(columns = ['at'])
        #useful_frame['from'] = datetime.datetime.fromtimestamp(int(useful_frame['from'])).strftime('%Y-%m-%d %H:%M:%S')
        useful_frame = useful_frame.set_index(useful_frame['from']).drop(columns = ['id'])
        main = main.append(useful_frame)
        main.drop_duplicates()
    final_data = main.drop(columns = {'to'})
    final_data = final_data.loc[~final_data.index.duplicated(keep = 'first')]

Since df.append() will be deprecated, I'm struggling to execute the same instructions using df.concat(). But I'm not getting it, how could I change that?

CodePudding user response：

Create an empty python list and then append all the series to the list. Finally call pandas' concat on that list, this will give you that dataframe.

CodePudding user response：

I think this is what you're looking for:

current = self.getAllCandles(self.active_id, start_candle)
frames = []
for candle in current:
    useful_frame = pd.DataFrame.from_dict(candle, orient='columns')
    #useful_frame['from'] = datetime.datetime.fromtimestamp(int(useful_frame['from'])).strftime('%Y-%m-%d %H:%M:%S')
    useful_frame = useful_frame.set_index('from')
    useful_frame = useful_frame.drop(columns=['at', 'id'])
    frames.append(useful_frame)

main = pd.concat(frames).drop_duplicates()
final_data = main.drop(columns='to')
final_data = final_data.loc[~final_data.index.duplicated()]