Python Get all activity before an activity according to a condition

I hope you can help me, I want to get all the activity according to a condition.

I have a dataframe like this:

I have as Target Activity Dress Up, so I should look for the Number of the activity and remove all the number after the number of target activity The output:

I have tried to use the function where but it removes all rows expect the one with target activity:

df= pd.read_csv('data.csv')
End_act = 'Dress Up'
cond = df['Activity']==Endact
df = df[  df['Number']<= df['Number'].where(cond)]

>Solution :

Use GroupBy.cummax with compare values by End_act in column Activity with change order rows by DataFrame.iloc for set Trues by all previous rows by End_act, last change order by original and filter in boolean indexing:

End_act = 'Dress Up'
m = (df.iloc[::-1]
       .assign(new = lambda x: x['Activity'].eq(End_act))
       .groupby('ID')['new']
       .cummax())

df = df[m.iloc[::-1]]
print (df)
   ID  Number  Activity
0   1       1    Get Up
1   1       2      Wash
2   1       3  Dress Up
3   2       1    Get Up
4   2       2  Dress Up

Your solution is changed with DataFrameGroupBy.idxmax for maximal index created by column Number:

End_act = 'Dress Up'
s = (df.set_index('Number')
        .assign(new = lambda x: x['Activity'].eq(End_act))
        .groupby('ID')['new']
        .transform('idxmax'))

df = df[df['Number'].le(s.to_numpy())]
print (df)
   ID  Number  Activity
0   1       1    Get Up
1   1       2      Wash
2   1       3  Dress Up
3   2       1    Get Up
4   2       2  Dress Up