timed_update_dataframe.py

import numpy as np
import pandas as pd
import time

N = int(1e7)
M = 100 

counter = 0 

df = pd.DataFrame({'y1': np.zeros(N)})

t0 = time.time()
while counter < N:
    df['y1'].values[counter:counter+M] = counter
    counter += M
tf = time.time()
print('update data frame:', tf - t0)

y = np.zeros(N)

t0 = time.time()
counter = 0 
while counter < N:
    y[counter:counter+M] = counter
    counter += M
df['y2'] = y 
tf = time.time()
print('update array:', tf - t0) 

assert (df.y1.values == df.y2.values).all()