Cut value in creating table - r

Question

I have following type of data:
mydata <- data.frame (yvar = rnorm(200, 15, 5), xv1 = rep(1:5, each = 40),
xv2 = rep(1:10, 20))
table(mydata$xv1, mydata$xv2)
1 2 3 4 5 6 7 8 9 10
1 4 4 4 4 4 4 4 4 4 4
2 4 4 4 4 4 4 4 4 4 4
3 4 4 4 4 4 4 4 4 4 4
4 4 4 4 4 4 4 4 4 4 4
5 4 4 4 4 4 4 4 4 4 4
I want tabulate again with yvar categories. The following is cutkey.
cutkey :
< 10 - group 1
10-12 - group 2
12-16 - group 3
>16 - group 4
Thus we will have similar to above type of table to each cutkey elements. I want to have margin sums everytime.
< 10 - group 1
1 2 3 4 5 6 7 8 9 10
1 4 4 4 4 4 4 4 4 4 4
2 4 4 4 4 4 4 4 4 4 4
3 4 4 4 4 4 4 4 4 4 4
4 4 4 4 4 4 4 4 4 4 4
5 4 4 4 4 4 4 4 4 4 4
10-12 - group 2
1 2 3 4 5 6 7 8 9 10
1 4 4 4 4 4 4 4 4 4 4
2 4 4 4 4 4 4 4 4 4 4
3 4 4 4 4 4 4 4 4 4 4
4 4 4 4 4 4 4 4 4 4 4
5 4 4 4 4 4 4 4 4 4 4
and so on for all groups
(the numbers will be definately different)
Is there easyway to do it ?

Answer 1

Yes, using cut, dlply (plyr package) and addmargins:
mydata$yvar1 <- cut(mydata$yvar,breaks = c(-Inf,10,12,16,Inf))
> dlply(mydata,.(yvar1),function(x) addmargins(table(x$xv1,x$xv2)))
$`(-Inf,10]`
1 2 3 4 5 6 7 8 9 10 Sum
1 0 0 0 0 0 0 2 0 1 0 3
2 1 1 0 1 0 0 0 0 2 0 5
3 0 1 0 0 1 1 0 2 0 0 5
4 0 0 2 0 1 1 0 1 0 0 5
5 0 1 1 0 1 1 1 0 0 2 7
Sum 1 3 3 1 3 3 3 3 3 2 25
$`(10,12]`
1 2 3 4 6 7 8 9 10 Sum
1 0 0 0 1 2 0 0 0 0 3
2 0 0 1 0 0 1 0 0 1 3
3 0 1 0 1 1 2 0 0 1 6
4 0 1 0 0 0 0 0 0 0 1
5 1 0 1 1 1 0 1 1 2 8
Sum 1 2 2 3 4 3 1 1 4 21
$`(12,16]`
1 2 3 4 5 6 7 8 9 10 Sum
1 2 3 1 1 1 2 0 3 0 2 15
2 0 1 0 1 3 3 2 0 0 1 11
3 3 1 3 1 0 0 0 2 4 1 15
4 3 2 1 2 2 0 1 1 4 1 17
5 3 1 1 2 0 1 1 1 1 0 11
Sum 11 8 6 7 6 6 4 7 9 5 69
$`(16, Inf]`
1 2 3 4 5 6 7 8 9 10 Sum
1 2 1 3 2 3 0 2 1 3 2 19
2 3 2 3 2 1 1 1 4 2 2 21
3 1 1 1 2 3 2 2 0 0 2 14
4 1 1 1 2 1 3 3 2 0 3 17
5 0 2 1 1 3 1 2 2 2 0 14
Sum 7 7 9 9 11 7 10 9 7 9 85
attr(,"split_type")
[1] "data.frame"
attr(,"split_labels")
yvar1
1 (-Inf,10]
2 (10,12]
3 (12,16]
4 (16, Inf]
You can adjust the breaks argument to cut to get the values just how you want them. (Although the margin sums you display in your question don't look like margin sums at all.)