Problem

DataFrame students

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+-------------+--------+
| Column Name | Type |
+-------------+--------+
| student_id | int |
| name | object |
| age | int |
| grade | float |
+-------------+--------+

Write a solution to correct the errors:

The grade column is stored as floats, convert it to integers.

The result format is in the following example.

Examples

Example 1

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Input: DataFrame students:
+------------+------+-----+-------+
| student_id | name | age | grade |
+------------+------+-----+-------+
| 1          | Ava  | 6   | 73.0  |
| 2          | Kate | 15  | 87.0  |
+------------+------+-----+-------+
Output: +------------+------+-----+-------+
| student_id | name | age | grade |
+------------+------+-----+-------+
| 1          | Ava  | 6   | 73    |
| 2          | Kate | 15  | 87    |
+------------+------+-----+-------+
Explanation: 
The data types of the column grade is converted to int.

Solution

Method 1 – Pandas astype Conversion

Intuition

The task is to convert the ‘grade’ column from float to int. This is a direct use of pandas’ type conversion capabilities.

Approach

  1. Use the astype(int) method on the ‘grade’ column to convert its type from float to int.
  2. Return the modified DataFrame.

Code

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import pandas as pd

def changeDataType(students: pd.DataFrame) -> pd.DataFrame:
    students['grade'] = students['grade'].astype(int)
    return students

Complexity

  • ⏰ Time complexity: O(n), where n is the number of rows.
  • 🧺 Space complexity: O(1) extra (in-place conversion).