0

I have a df like this:

Year        2016    2017    
Month               
1       0.979000    1.109000    
2       0.974500    1.085667    
3       1.004000    1.075667    
4       1.027333    1.184000    
5       1.049000    1.089000    
6       1.013250    1.085500    
7       0.999000    1.059000    
8       0.996667    1.104000    
9       1.024000    1.121333    
10      1.019000    1.126333    
11      0.949000    1.183000    
12      1.074000    1.203000

How can I add a 'Season' column that populates "Spring", "Summer" etc. based on the numerical value of month? E.g months 12, 1, and 2 = Winter, etc?

jros112
  • 151
  • 1
  • 5
  • 3
    kindly post your expected output. Looking at your data from face value, a `map` could do it for you, with a dictionary. ``df.assign(season = df.Month.map({1:'Spring',2:'Winter', ...})`` – sammywemmy Sep 26 '21 at 23:51
  • It looks like Month is the `index` not a column is that correct? – Henry Ecker Sep 27 '21 at 00:08

2 Answers2

0

You could use np.select with pd.Series.between:

import numpy as np
df["Season"] = np.select([df["Month"].between(3, 5), 
                          df["Month"].between(6, 8),
                          df["Month"].between(9, 11)], 
                          ["Spring", "Summer", "Fall"], 
                          "Winter")

    Month      2016      2017  Season
0       1  0.979000  1.109000  Winter
1       2  0.974500  1.085667  Winter
2       3  1.004000  1.075667  Spring
3       4  1.027333  1.184000  Spring
4       5  1.049000  1.089000  Spring
5       6  1.013250  1.085500  Summer
6       7  0.999000  1.059000  Summer
7       8  0.996667  1.104000  Summer
8       9  1.024000  1.121333    Fall
9      10  1.019000  1.126333    Fall
10     11  0.949000  1.183000    Fall
11     12  1.074000  1.203000  Winter
not_speshal
  • 22,093
  • 2
  • 15
  • 30
-1

You could iterate through the column, appending data to a new data frame which you will add in as a column.

for i in df['Year Month'] :
    if i == 12 or 1 or 2 :
        i = "Winter"
        df2.append(i)

Then add on your other conditions with elif and else statements and you should be good to add it onto your main df afterwards. Lemme know if this helps.

Joseph Hogan
  • 58
  • 8
  • 1
    You [shouldn't](https://stackoverflow.com/a/55557758/9857631) iterate over a DataFrame when there are vectorized solutions available. As an aside, you are overwriting your `for` loop variable `i` within the loop (with "Winter"). And your condition should be `if i==12 or i==1 or i==2`. – not_speshal Sep 27 '21 at 00:04
  • 1
    `i == 12 or 1 or 2` is always `True` [Why does `a == x or y or z` always evaluate to True?](https://stackoverflow.com/q/20002503/15497888) – Henry Ecker Sep 27 '21 at 00:05
  • @not_speshal thank you I was not aware of that – Joseph Hogan Sep 27 '21 at 18:53
  • 1
    @JosephHogan - All good. PS - I wasn't the downvoter (I also got downvoted) – not_speshal Sep 27 '21 at 18:55