Data Analysis with R, Second Edition - Second Edition

Checking for out-of-bounds data

It's common for numeric values in a column to have a natural constraint on the values that it should hold. For example, if a column represents a percent of something, we might want to check if all the values in that column are between zero and one (or 0 and 100). In assertr, we typically use the within_bounds function in conjunction with the assert verb to ensure that this is the case. For example, if we added a column to mtcars that represented the percent of the heaviest car's weight, the weight of each car is:

library(assertr) 
mtcars.copy <- mtcars 
 
mtcars.copy$Percent.Max.Wt <- round(mtcars.copy$wt /  
                                    max(mtcars.copy$wt), 
                                    2) 
 
mtcars.copy <- assert(mtcars.copy, within_bounds(0,1), 
                     Percent.Max.Wt) 

within_bounds ...