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Data Foundations · A little practice goes a long way.

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Selecting data · I10 · 8 MIN

Filter rows

Keep rows where a condition is true.

Exercises within this concept

  1. FollowFollow the techniqueCurrent exercise
  2. ChangeUse category membership
  3. TransferUse an inclusive interval

Understand the idea

A condition creates a True/False flag for each row. df[mask] returns the whole rows whose flags are True.

Concept sketch: price > 2: keep matching rowsrowpriceA2B4C3rowpriceB4C3price > 2: keep matching rows
Illustration · not the exercise output

A small example

For ages [2, 4, 6], age > 4 gives [False, False, True]; filtering keeps only the row with age 6.

Follow the code

Apply the idea to the supplied table. Read from top to bottom; the final line displays the result.

df[df["price"] > 2.1]

What each part does

df["price"] > 2.1
Test each price; the result is one True or False per row.
df[mask]
keep rows where mask is True
Other choices for later exercises
==
compare values; = assigns a value

Your inputs

The editable setup on the right creates df. Run executes the setup and your work from top to bottom.

Candy shop · 6 synthetic rows
candyflavourpriceratingshelf
Gummy Bearfruity1.24.1A
Choco Popchocolate2.14.6B
Mint Bitemint1.53.8A
Berry Loopfruity2.84.4B
Cocoa Cubechocolate3.44.9A
Lemon Dropfruity1.84B

Your task · Follow

Using df, keep every row where price is greater than 2.1.

Hint

The comparison makes a mask; df[mask] selects the rows where it is True.

Reveal solution

One way to do it. Keep any supplied setup in the editor and use this in the Your work section.

df[df["price"] > 2.1]
Your task · Follow

Using df, keep every row where price is greater than 2.1.

Tab: indent · Shift+Tab: outdent · Esc, then Tab: leave editor

Edit Python. Control or Command plus Enter runs it. Tab indents by four spaces. Shift plus Tab outdents. Press Escape, then Tab or Shift plus Tab to leave the editor.

Each run executes all editor code in a fresh Python session. Display a value by leaving it on the final line.

Python starts when you open a lesson.

Output

Run your code to see what Python returns.