Question

I have a data frame and I’m trying to run a subset on it. In my data frame, I have a column called “start” and I’m trying to do this:

sub <- subset(data,data$start==14)

and I correctly get a subset of all the rows where start=14.

But, when I do this:

for(start in seq(1,20,by=1)) {
   sub <- subset(data,data$start==start)
   print(sub)
}

it does not correctly find the subsets. It just prints the entire data frame.

Why is this and how do I fix it?

Answer 1

You can also specify the environment you’re working with:

x<-data.frame(
  start=sample(3,20,replace=TRUE),
  someValue=runif(20))

env<-environment()
start<-3
cat("\nDefaut scope:")
print(subset(x,start==start)) # all entries, as start==start is evaluated to TRUE

cat("\nSpecific environment:")
print(subset(x,start==get('start',env)))  # second start is replaced by its value in former environment. Equivalent to subset(x,start==3)