String formatting with sprintf in R Programming

Introduction

String formatting with sprintf helps you create neat and readable text by inserting values into a template.

When you want to show numbers with a fixed number of decimal places.

When you need to combine text and numbers in a clear sentence.

When you want to align text or numbers in columns.

When you want to format dates or times in a specific way.

When you want to prepare messages for reports or user display.

Syntax

R Programming

sprintf(format, ...)

The format is a string that tells how to insert values, using placeholders like %s for text, %d for integers, and %f for floating-point numbers.

You can control width, precision, and alignment inside the format string.

Examples

Inserts the text 'Alice' into the placeholder %s.

R Programming

sprintf("Hello %s!", "Alice")

Inserts the integer 5 into the placeholder %d.

R Programming

sprintf("You have %d new messages.", 5)

Formats the number 3.14159 to show 2 decimal places.

R Programming

sprintf("Pi is approximately %.2f.", 3.14159)

Left-aligns 'Item' in 10 spaces and right-aligns 42 in 5 spaces.

R Programming

sprintf("%-10s %5d", "Item", 42)

Sample Program

This program creates a message greeting Bob and showing his score rounded to one decimal place.

R Programming

name <- "Bob"
score <- 87.456
message <- sprintf("Hello %s, your score is %.1f.", name, score)
print(message)

Important Notes

If you use the wrong placeholder for a value type, sprintf may give an error or unexpected result.

You can use %% to print a literal percent sign in the output.

sprintf returns the formatted string; it does not print it unless you use print() or cat().

Summary

sprintf helps build strings by inserting values into a template.

Use placeholders like %s, %d, and %f to control how values appear.

It is useful for making messages, reports, and aligned text.