Create a new column in a dataframe containing string values from different columns based on values in another column of a dataframe

Question


channel_paths['path'] = np.where(
    channel_paths['conversion'] == 0,
    ['Start'] + channel_paths['channel'] + ['Null'],
    ['Start'] + channel_paths['channel'] + ['Conversion'])

I would like to add string Null at the end if conversion is 0 and add conversion column value if conversion value is 1 .

`I have a below error

TypeError: Cannot broadcast np.ndarray with operand of type <class 'list'>

Remove the brackets around 'Start', 'Null', and 'Conversion' to use strings instead of lists — Leo
– Leo, Commented Jun 14, 2021 at 18:25
See below error with those changes TypeError: can only concatenate str (not "list") to str — Gangadhar Dixit
– Gangadhar Dixit, Commented Jun 14, 2021 at 18:37

Andrej Kesely · Accepted Answer · 2021-06-15 07:18:22Z

1

If you have dataframe like this:

  channel  conversion
0     xxx           0
1     yyy           1

Then this will create new "path" column:

df["path"] = np.where(
    df["conversion"] == 0,
    df["channel"] + "Null",
    df["channel"] + df["conversion"].astype(str),
)

print(df)

Prints:

  channel  conversion     path
0     xxx           0  xxxNull
1     yyy           1     yyy1

EDIT: To append to a list in column "channel":

df.apply(lambda x:  x['channel'].append('Null') if x['conversion'] == 0 else x['channel'].append(x['conversion']), axis=1)
print(df)

Prints:

       channel  conversion
0  [xxx, Null]           0
1     [yyy, 1]           1

edited Jun 15, 2021 at 7:18

answered Jun 14, 2021 at 19:03

Andrej Kesely

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1 Comment

Gangadhar Dixit Over a year ago

But my channel is a list of string which is causing issue

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