Truncate but NOT Round in R [duplicate]

Question

Really basic, but Googling didn't yield an answer. Is there a way to truncate a numeric value without rounding it?

For example:

vars <- c(23.4567, 45.6795, 34.5670)

I want the output to simply lob off the last two significant figures, but not round the output. What I want is:

vars <- c(23.45, 45.67, 34.56)

But the most common ways of doing this end up rounding (round, of course, but also signif:

round(vars, 2)

[1] 23.46 45.68 34.57

signif(vars, digits=4)

[1] 23.46 45.68 34.57

Please point me in the right direction if this has already been addressed here, but couldn't find it specific to R...

Answer 1

You could try with floor()

vars <- floor(vars*100)/100

However, this solution assumes that all values are positive, as floor() rounds to the next lower integer. If there are negative numbers this approach could yield undesirable results:

> floor(-23.441*100)/100
#[1] -23.45

A more general solution therefore consists in using trunc():

vars <- trunc(vars*100)/100

This will remove any digit after the first two decimals, and it also works for negative numbers:

> trunc(-23.441*100)/100
#[1] -23.44

Answer 2

You could use the floor() function, with a little extra help.

floor(100*vars)/100