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Practice

Selecting Columns and Rows

When analyzing data, you often need to focus on specific parts — like selecting a column of interest or checking a few rows.

In Pandas, this is done using column labels, row positions, and index labels.


Selecting Columns

The most reliable way to select a column is with square brackets and the column name:

Select a column by name
df["Population"]

This returns a Series. You can also assign it to a variable, combine it with conditions, or perform calculations.

Avoid using df.ColumnName (dot notation). It works only when column names are valid Python identifiers.


Selecting Rows

To select rows, use either:

  • iloc[] for position-based access
  • loc[] for label-based access
Select the first row by position
df.iloc[0]
Select the row with label 0
df.loc[0]

These return a row as a Series.


Selecting a Specific Value

You can combine row and column selection to get a single cell value:

Select a single value
df.loc[0, "Population"]

This gives you the value at row 0, column "Population".


Summary Table

SelectorAccess TypeExample
df["col"]Column by namedf["Age"]
df.iloc[i]Row by positiondf.iloc[3]
df.loc[i]Row by labeldf.loc[3]
df.loc[i, "col"]Celldf.loc[3, "Age"]

What’s Next?

Now that you know how to select data, let’s filter it using conditions!

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