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This approach focuses on manipulating the data structures that hold the DataFrame or its equivalent to rename the columns. The idea is to access the data structure directly and modify the column headers.
Time Complexity: O(1) as renaming columns in a DataFrame does not depend on the number of rows.
Space Complexity: O(1), no additional space required beyond the rename operation.
1import pandas as pd
2
3def rename_columns
In Python, the Pandas library provides a rename function which can easily rename columns. The rename method takes a dictionary where keys are existing column names and values are the new names.
This approach relies on using specific libraries available for each programming language that are geared towards data manipulation. These libraries often offer built-in functionalities for renaming columns effortlessly.
Time Complexity: O(1) since column renaming is independent of the data in the table.
Space Complexity: O(1) because it modifies column names in-place.
1import java.util.ArrayList;
2import java.util.HashMap;
3import java.util.List;
4import java.util.Map;
5
6class Student {
7 int student_id;
8 String first_name;
9 String last_name;
10 int age_in_years;
11
12 Student(int id, String first, String last, int age) {
13 this.student_id = id;
14 this.first_name = first;
15 this.last_name = last;
16 this.age_in_years = age;
17 }
18
19 @Override
20 public String toString() {
21 return student_id + ", " + first_name + ", " + last_name + ", " + age_in_years;
22 }
23}
24
25public class Main {
26 public static void main(String[] args) {
27 List<Map<String, Object>> students = new ArrayList<>();
28 addStudent(students, 1, "Mason", "King", 6);
29 addStudent(students, 2, "Ava", "Wright", 7);
30 addStudent(students, 3, "Taylor", "Hall", 16);
31 addStudent(students, 4, "Georgia", "Thompson", 18);
32 addStudent(students, 5, "Thomas", "Moore", 10);
33
34 List<Student> renamedStudents = renameColumns(students);
35 for (Student student : renamedStudents) {
36 System.out.println(student);
37 }
38 }
39
40 static void addStudent(List<Map<String, Object>> list, int id, String first, String last, int age) {
41 Map<String, Object> student = new HashMap<>();
42 student.put("id", id);
43 student.put("first", first);
44 student.put("last", last);
45 student.put("age", age);
46 list.add(student);
47 }
48
49 static List<Student> renameColumns(List<Map<String, Object>> original) {
50 List<Student> renamed = new ArrayList<>();
51 for (Map<String, Object> entry : original) {
52 renamed.add(new Student(
53 (int) entry.get("id"),
54 (String) entry.get("first"),
55 (String) entry.get("last"),
56 (int) entry.get("age")
57 ));
58 }
59 return renamed;
60 }
61}In Java, without a direct DataFrame equivalent, we use a List of Maps to simulate the data structure. We rename columns by reconstructing the map into a custom class instance expressing the new naming.