SQA Tools Blog

Learn testing and automation, one article at a time

Free tutorials, solved practice problems and interview prep for QA and automation engineers: Python, Playwright, Selenium, SQL, Git and more.

1,677Articles
1,141Solved Python problems
7Topics
100%Free

Python practice articles

1,137 articles · page 38 of 95 · Clear filters
Python practice

Fill from the next row

Write a pandas program to replace NaN with the value from the next row. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Fill from the previous row

Write a pandas program to replace NaN with the value from the previous row. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Drop rows that are entirely missing

Write a pandas program to drop rows where all values are missing. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Drop columns with missing values

Write a pandas program to drop columns where at least one value is missing. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Drop rows with any missing value

Write a pandas program to drop rows where at least one value is missing. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Missing values per column

Write a pandas program to count the missing values in each column. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Columns with missing values

Write a pandas program to find the columns with at least one missing value. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Detect missing values

Write a pandas program to show where values are missing. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Merge with different columns

Write a pandas program to merge two DataFrames with different columns, keeping all rows. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Merge on a common column

Write a pandas program to join two DataFrames on their common column. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Join along columns

Write a pandas program to join two DataFrames side by side. Step-by-step explanation, colour-coded code and real output.

1 min readRead →
Python practice

Join along rows

Write a pandas program to join two DataFrames along rows. Step-by-step explanation, colour-coded code and real output.

1 min readRead →

Preparing for a QA interview?

Take free timed mock tests with answers and explanations.