Ranking in python dataframe-CodePudding

I have data of cooking oil and its boiling temp and try to rank it by higher boiling temp. I'm using these code below:

df['ranking']=df['boil_temp'].rank(ascending=False)
df = df.set_index('ranking')

df_ranked = df.sort_values(by=['ranking'],ascending=True)
print(df_ranked)

                      oil  boil_temp
Ranking                             
1.0               avocado        270
2.0             sunflower        252
4.0           beef_tallow        250
4.0      butter_clarified        250
4.0               mustard        250
6.0                  palm        235
7.0                  corn        230
8.0             grapeseed        216
9.0                canola        204
10.0              coconut        200
11.0             olive_ev        160
12.0               butter        150

But I want the rank to be like this:

                      oil  boil_temp
Ranking                             
1.0               avocado        270
2.0             sunflower        252
3.0           beef_tallow        250
3.0      butter_clarified        250
3.0               mustard        250
4.0                  palm        235
5.0                  corn        230
6.0             grapeseed        216
7.0                canola        204
8.0               coconut        200
9.0              olive_ev        160
10.0               butter        150

What should I do?

CodePudding user response：

An interesting thing about the rank function is that if there is a tie between N previous records for the value in the column, the rank function skips the next N-1 positions before incrementing the counter.

However the dense rank function does not skip any ranks if there is a tie between the ranks of the preceding records

Addition to what @bb1 has suggested -

>>> df['Ranking'] = df['boil_temp'].rank(ascending=False, method='dense')

>>> df = df.sort_values(by='Ranking', ascending=True)

>>> df.reset_index(drop=True, inplace=True)

>>> print(df)

Ranking               Oil  boil_temp
0       1.0           avocado        270
1       2.0            canola        260
2       3.0         sunflower        252
3       4.0       beef_tallow        250
4       4.0  butter_clarified        250
5       4.0           mustard        250
6       5.0              palm        235
7       6.0              corn        230
8       7.0         grapeseed        216
9       8.0           coconut        200
10      9.0          olive_ev        160
11     10.0            butter        150