Replacing values from a column using a condition in R

Question

I have a very basic R question but I am having a hard time trying to get the right answer. I have a data frame that looks like this:

 ind<-re         


        

Answer 1

# reassign depth values under 10 to zero
df$depth[df$depth<10] <- 0

(For the columns that are factors, you can only assign values that are factor levels. If you wanted to assign a value that wasn't currently a factor level, you would need to create the additional level first:

levels(df$species) <- c(levels(df$species), "unknown") 
df$species[df$depth<10]  <- "unknown"