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Transpose File

Problem Description​

Given a text file file.txt, transpose its content.

You may assume that each row has the same number of columns and each field is separated by the ' ' character.

Example​

Example 1:

Assume that `file.txt` has the following content:
name age
alice 21
ryan 30

Your script should output the following transposed content:
name alice ryan
age 21 30

Constraints​

  • The file file.txt will be at most 10^3 lines.
  • Each line in the file will have at most 10^3 characters.
  • Each field in the file is separated by a single space character.

Solution Approach​

Approach Overview​

We can use a combination of awk, paste, and cut commands in a bash script to transpose the content of the file.

Detailed Steps​

  1. Read Each Line and Store Columns:
    • Use awk to read each line and store columns in arrays.
  2. Print Transposed Content:
    • Loop through the columns and print them as rows.

Code Examples​

Shell Script​

awk '
{
    for (i = 1; i <= NF; i++) {
        if (NR == 1) {
            s[i] = $i;
        } else {
            s[i] = s[i] " " $i;
        }
    }
}
END {
    for (i = 1; i <= NF; i++) {
        print s[i];
    }
}
' file.txt

Complexity​

  • Time Complexity: O(n * m), where n is the number of rows and m is the number of columns. Each element is processed once.

  • Space Complexity: O(n * m), as we store each element in memory to perform the transposition.