Set value for particular cell in pandas DataFrame using index

Question

I\'ve created a Pandas DataFrame

df = DataFrame(index=[\'A\',\'B\',\'C\'], columns=[\'x\',\'y\'])

and got this

    x    y
A  NaN         


        

Answer 1

I tested and the output is df.set_value is little faster, but the official method df.at looks like the fastest non deprecated way to do it.

import numpy as np
import pandas as pd

df = pd.DataFrame(np.random.rand(100, 100))

%timeit df.iat[50,50]=50 # ✓
%timeit df.at[50,50]=50 #  ✔
%timeit df.set_value(50,50,50) # will deprecate
%timeit df.iloc[50,50]=50
%timeit df.loc[50,50]=50

7.06 µs ± 118 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
5.52 µs ± 64.2 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
3.68 µs ± 80.8 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)
98.7 µs ± 1.07 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)
109 µs ± 1.42 µs per loop (mean ± std. dev. of 7 runs, 10000 loops each)

Note this is setting the value for a single cell. For the vectors loc and iloc should be better options since they are vectorized.