freeCodeCamp/curriculum/challenges/italian/08-data-analysis-with-python/data-analysis-with-python-course/data-cleaning-introduction.md

id	title	challengeType	videoId	dashedName
5e9a093a74c4063ca6f7c15d	Data Cleaning Introduction	11	ovYNhnltVxY	data-cleaning-introduction

--description--

Instead of using notebooks.ai like it shows in the video, you can use Google Colab instead.

More resources:

• Notebooks on GitHub
• How to open Notebooks from GitHub using Google Colab.

--question--

--text--

What will the following code print out?

import pandas as pd
import numpy as np

s = pd.Series(['a', 3, np.nan, 1, np.nan])

print(s.notnull().sum())

--answers--

3

---

0     True
1     True
2    False
3     True
4    False
dtype: bool

---

0    False
1    False
2     True
3    False
4     True
dtype: bool

--video-solution--

1