How can I achieve fixed-width alignment of printed strings in Python?

Printing Strings with Fixed Width Alignment

In programming, it's often desirable to align strings in fixed columns for clarity and visual organization. This article explores how to achieve this using advanced formatting techniques in Python.

Problem: Aligning Uneven String Values

Consider the following code that calculates the frequency of all permutations in a given string:

# Original code to generate permutations
...

# Printing results
unique = sorted(set(el))
for prefix in unique:
    if prefix != "":
        print("value  ", prefix, "- num of occurrences =   ", string.count(str(prefix)))

However, the output may appear misaligned due to varying string lengths:

value   a - num of occurrences =    1
value   ab - num of occurrences =    1
value   abc - num of occurrences =    1
value   b - num of occurrences =    1
value   bc - num of occurrences =    1
value   bcd - num of occurrences =    1
value   c - num of occurrences =    1
value   cd - num of occurrences =    1
value   d - num of occurrences =    1

Solution Using str.format

To align the output, we can utilize the str.format method with specific format specifiers:

# Using str.format for alignment
print("{0: <5}".format("value  ") +
      "{1: >15}".format(prefix) +
      "- num of occurrences =   " +
      "{2: <5}".format(string.count(str(prefix))))

Format Specifiers:

• <5: Left-align the string within a 5-character width.
• >15: Right-align the string within a 15-character width.

  Edit 1: The "0" in "{0: <5}" refers to the index of the argument passed to str.format().

  Edit 2: Python 3 introduces f-strings as a concise alternative to str.format:

  # Using f-strings for alignment
  print(f"{'value  ':<5}" +
        f"{prefix:>15}" +
        "- num of occurrences =   " +
        f"{string.count(str(prefix)):<5}")</p>

  Advantages:

  • Enhanced readability and organization.
  • Flexibility in specifying alignment and width.
  • Compatibility with both Python 2 and Python 3.

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