Pandas replace NaN value by string under conditions

Question

What I am trying to do is to replace the NaN value by a string 'school'. If longitude is within the range of 114.8 to 115.2 and latitude is within the range of 19.8 to 20.2, the NaN value in the location column with be replaced by the string 'School'.

df=
    Date            Longitude Latitude   Location
0   2020-01-01 01:00    115.1   20.0         NaN 
1   2020-01-01 01:01    115.0   20.1         NaN
2   2020-01-01 01:02    114.9   19.9         NaN
3   2020-01-01 01:03    123.1   20.0         NaN
4   2020-01-01 01:04    115.0   18.9         NaN

I would like to convert my DataFrame as follows

df=
    Date            Longitude Latitude   Location
0   2020-01-01 01:00    115.1   20.0      school
1   2020-01-01 01:01    115.0   20.1      school
2   2020-01-01 01:02    114.9   19.9      school
3   2020-01-01 01:03    123.1   20.0       NaN
4   2020-01-01 01:04    115.0   18.9       NaN

What I have tried to do is

df.loc[((df['Longitude']<115.2) & (df['Longitude']>114.8) & (df['Latitude']>19.8) & (df['Latitude']<20.2)), df['Location']]='School'

However, I get an error

KeyError: "None of [Float64Index([nan, nan, nan, nan, nan, nan, nan, nan, nan, nan,\n              ...\n              nan, nan, nan, nan, nan, nan, nan, nan, nan, nan],\n             dtype='float64', length=7441)] are in the [columns]"
    

I am not sure why this is happening and thx a lot for reading my question!

Answer 1

You are close:

df.loc[((df['Longitude']<115.2) & (df['Longitude']>114.8) 
         & (df['Latitude']>19.8) & (df['Latitude']<20.2)), 
      'Location']='School'

Also, you can use between :

df.loc[((df['Longitude'].between(114.8, 115.2, inclusive=False) 
         & (df['Latitude'].between(19.8, 20.2, inclusive=False)), 
      'Location']='School'

Answer 2

After the condition in df.loc[] a column name is expected as key and you are passing the series df['Location'] which ends up giving you the key error.

mention only the column name ie 'Location' and it will work.

df.loc[((df['Longitude']<115.2) & (df['Longitude']>114.8) & 
      (df['Latitude']>19.8) & (df['Latitude']<20.2)), 
      'Location'] = 'School'

Answer 3

Try using just numpy where method:

df['location'] = np.where((df['Longitude'].between(114.8, 115.2)) & ((df['Latitude'].between(19.8, 20.2)), "school", np.nan)