Fill Random Marks

import numpy as np
import pandas as pd
datatype = [('Science', 'int32'), ('Maths', 'int32')]
current_values = np.zeros(3, dtype=datatype)
current_index = ['Row '+str(i) for i in range(1, 4)]
df = pd.DataFrame(current_values, index=current_index)
df
Science Maths
Row 1 0 0
Row 2 0 0
Row 3 0 0 
df['Science']
Row 1    0
Row 2    0
Row 3    0
Name: Science, dtype: int32

df['Science'][0] = 45
df['Maths'][1] = 100
df
Science Maths
Row 1 45 0
Row 2 0 100
Row 3 0 0 
df.shape
(3, 2)