计算 Pandas 组内列的百分比变化

Question

My dataframe has a Ticker column and a Price column. There are 10 rows per Ticker (with the same Ticker value) but each row has a different Price.

My aim is to calculate the percent change within a Ticker group.

I tried the following but failed:

Test_preds_actual1['Target1_preds_pct_chng'] = 0
Test_preds_actual1.groupby('Ticker')['Target1_preds_pct_chng'] =\
Test_preds_actual1.groupby('Ticker')['Target1_preds'].pct_change()

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-316-168796f850f9> in <module>
      1 Test_preds_actual1.groupby('Ticker')['Target1_preds_pct_chng'] =\
----> 2 Test_preds_actual1.groupby('Ticker')['Target1_preds'].pct_change()

TypeError: 'DataFrameGroupBy' object does not support item assignment

I am not sure I understand the error message. How can I accomplish my objective?

Answer 1

你可以做分配

Test_preds_actual1['Target1_preds_pct_chng']=Test_preds_actual1.groupby('Ticker')['Target1_preds'].pct_change()