Assign variables to df with condition and range-CodePudding

I have a dataframe:

task_name task_id project_id user
zoo      10       100      Nan
zoo      11       110      Nan
foo      22       100      Nan
foo      23       110      Nan
xyz      33       100      Nan
xyz      34       110      Nan
qwe      40       100      Nan

Where task_name common, task_id is unique and proejct_id two variables. So same task_name in two dif project_id and unique task_id.
I need to assign to column user at users but with several condition:
First: all users have coefficient(factor) how many tasks can be assign to this user, for example only 4 from this df. Second: for each user can be assign only one task_name, for example user 'dude' can be assign to task_name zoo with task_id 10 in project_id 100 but not in both task_name zoo with task_id 10 and 11 in project_id 100 and 110. So I need check no double assign in same task_name. My expect output:

task_name task_id project_id user
    zoo      10       100      dude
    zoo      11       110      user2
    foo      22       100      dude
    foo      23       110      user2
    xyz      33       100      dude
    xyz      34       110      user2
    qwe      40       100      dude

I trying this but without success:

df.apply(lambda x: 'dude' if x['project_id'] == 100 else np.nan, axis=1)
df.sort_values(by='project_id', inplace=True)
df['user'][0:4] = 'dude'

CodePudding user response：

From sample data seems solution should be simplify - if project_id is 100 assign dude else user2:

df['user'] = np.where(df['project_id'] == 100,'dude','user2')

If need assign first N values in sorted values:

df.sort_values(by='project_id', inplace=True, ignore_index=True)
df['user'] = np.where(df.index < 4, 'dude','user2')
print (df)
  task_name  task_id  project_id   user
0       zoo       10         100   dude
1       foo       22         100   dude
2       xyz       33         100   dude
3       qwe       40         100   dude
4       zoo       11         110  user2
5       foo       23         110  user2
6       xyz       34         110  user2