CODEWITHSUNDEEP
pythonpandas
nipy
nipy

Reputation: 5508

Concatenate string number to start of series index

I have the following series:

ser = pd.Series(["foo","bar","a",4,5], index=["a", "b", "c", "d", "e"])
ser

a    foo
b    bar
c      a
d      4
e      5
dtype: object

I want to concatenate an incrementing string number before the index as follows:

#desired output

0_a    foo
1_b    bar
2_c      a
3_d      4
4_e      5
dtype: object

I tried this:

increment = iter(range(0,10))

ser.index = str(next(increment))+"_"+ser.index

but the string number doesn't increment. How should I approach this?

Upvotes: 1

Views: 97

Answers (2)

foo31213
foo31213

Reputation: 1

ser.index.map(lambda x : str(next(increment))+x)

Upvotes: 0

jezrael
jezrael

Reputation: 863341

Use list comprehension with f-strings and enumerate:

ser.index = [f'{a}_{b}' for a, b in enumerate(ser.index)]

Or join RangeIndex converted to strings with str.cat:

ser.index = pd.RangeIndex(len(ser)).astype(str).str.cat(ser.index, sep='_')

Or:

ser.index = pd.RangeIndex(len(ser)).astype(str) + '_' + ser.index

print (ser)
0_a    foo
1_b    bar
2_c      a
3_d      4
4_e      5
dtype: object

Upvotes: 1

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