Replace all values in a matrix <0.1 with 0

Question

I have a matrix (2601 by 58) of particulate matter concentration estimates from an air quality model. Because real-life air quality monitors cannot measure below 0.1 ug/L,

Answer 1

Just to provide an (in my opinion) interesting alternative:

If you need to clamp the values so they are never smaller than a value, you could use pmax:

set.seed(42)
m <- matrix(rnorm(100),10)

m <- pmax(m, 0) # clamp negative values to 0

...This doesn't quite work in your case though since you want values < 0.1 to become 0.