format(x, trim=FALSE, digits=NULL)

Format an R object (e.g. a data frame) to print helpful information from a function.

- x – A data frame, matrix, or other R object.
- trim – Whether to prevent right-justification.
- digits – Number of digits to show.

Example. Below a table similar to that of regression output is created. The original data frame has an unnecessary number of digits in some rows when printed as-is. The format function output is cleaned up and includes fewer digits, making it easier to read the table.

> beta <- c(2.1, 6.21, 4.321, 5.4321) > SE <- c(5, 1.49, 11.13, 0.31) > t <- beta/SE > p.value <- 2*pt(-abs(t), 12) > > x <- data.frame(beta, SE, t, p.value) > row.names(x) <- c("HS GPA", "college", "gender", "age") > x beta SE t p.value HS GPA 2.1000 5.00 0.420000 6.819077e-01 college 6.2100 1.49 4.167785 1.304575e-03 gender 4.3210 11.13 0.388230 7.046453e-01 age 5.4321 0.31 17.522903 6.491560e-10 > > fx <- format(x, digits=3) > fx beta SE t p.value HS GPA 2.10 5.00 0.420 6.82e-01 college 6.21 1.49 4.168 1.30e-03 gender 4.32 11.13 0.388 7.05e-01 age 5.43 0.31 17.523 6.49e-10 > > fx[,1] [1] "2.10" "6.21" "4.32" "5.43"

Tip. Use format when printing a matrix or data frame as information from a function. This is especially useful when creating a print or summary method for a new class of objects. However, do not return a formatted object from a function since formatting turns numbers into character strings, adds spaces, rounds values, etc.