Python. Pandas Median value of a groupedby column

Question

I have a data frame here: https://www.dropbox.com/s/ja6kn0f55599xul/test.csv

So, I want to calculate the median value of df.bid but according to df.candle value, i.e.:

median df.bid for rows where df.candle is 0, median df.bid where df.candle is 1, median df.bid where df.candle is 2, etc for the whole data frame. I also would like to store it in a separate column.

I thought something like this would work:

df['median'] = df.bid.groupby('candle').mean()

But neither that nor this works:

df['median'] = df['bid'].groupby('candle').mean()

Both resulting in an error:

Traceback (most recent call last):
  File "C:/Users/irmsc/pp/fml/mo18.py", line 27, in <module>
    df['median'] = df['bid'].groupby('candle').mean()
  File "C:\Users\irmsc\pp\fml\venv\lib\site-packages\pandas\core\generic.py", line 7632, in groupby
    observed=observed, **kwargs)
  File "C:\Users\irmsc\pp\fml\venv\lib\site-packages\pandas\core\groupby\groupby.py", line 2110, in groupby
    return klass(obj, by, **kwds)
  File "C:\Users\irmsc\pp\fml\venv\lib\site-packages\pandas\core\groupby\groupby.py", line 360, in __init__
    mutated=self.mutated)
  File "C:\Users\irmsc\pp\fml\venv\lib\site-packages\pandas\core\groupby\grouper.py", line 578, in _get_grouper
    raise KeyError(gpr)
KeyError: 'candle'