Examples
import numpy as np
import pandas as pd
df = pd.DataFrame([[0, 3, 4], [0, 5, 2], [20, 30, 40]],
index=[1, 2, 3], columns=['P', 'Q', 'R'])
df
Get value at specified row/column pair:
df.at[1, 'Q']
Set value at specified row/column pair:
df.at[1, 'Q'] = 20
df.at[1, 'Q']
Get value within a Series:
df.loc[2].at['Q']