Group value in range r

Question

I have my table(input)

name   value
Rob    35
Helen  20
Sergey 16
Linn   40
Elena  23
Mary   40

And I want to count how many of my users is

Answer 1

Here is a full solution, including your sample data:

df <- data.frame(name=c("r", "h", "s", "l", "e", "m"), value=c(35,20,16,40,23,40))
# get categories
df$groups <- cut(df$value, breaks=c(0,21,30,Inf))

# calculate group counts:
table(cut(df$value, breaks=c(0,21,30,Inf)))

If Inf is a little too extreme, you can use max(df$value) instead.