Recursive SQL CTE query in Pandas?

Question

how do I elegantly port the below recursive SQL query to Pandas python code? Somehow I don\'t see a straightforward way without writing own recursive function?

Pytho

Answer 1

First, you need to correct the typo in python code MgrID list: [0,1,1,2,0,0,5,6]

Second, if this job is done recursively in SQL, why do you expect Python/Pandas can do it without recursive method? It isn't too hard:

def nlevel(id, mgr_dict=df.MgrID, _cache={0:0}):
    if id in _cache:
        return _cache[id]

    return 1+nlevel(mgr_dict[id],mgr_dict)

df['nLevel'] = df.ID.map(nlevel)

print df[['nLevel','ID','Name']]

Then the output(nLevel) is what you need (except the order, which I don't understand from your SQL):

    nLevel  ID    Name
ID                    
1        1   1   Keith
2        2   2    Josh
3        2   3   Robin
4        3   4    Raja
5        1   5  Tridip
6        1   6  Arijit
7        2   7    Amit
8        2   8     Dev

[8 rows x 3 columns]