What you are probably looking for is the %in% operator:
with(mydata, sum(table(X1[X2 %in% 5:8])))
Read up on how operations are vectorized and how variables are
recycled if not long enough
x - 1:10
x == 1:2 # compares first two fine
[1] TRUE TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
x == 1:3 # same for the first 3
[1] TRUE TRUE TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
x == 4:6 # this is 4 5 6 4 5 6 which just happens to compare with 4 5 6 in x
[1] FALSE FALSE FALSE TRUE TRUE TRUE FALSE FALSE FALSE FALSE
x == 2:5 # notice that this fail
[1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
x %in% c(8,2,7,3) # order not important
[1] FALSE TRUE TRUE FALSE FALSE FALSE TRUE TRUE FALSE FALSE
On Fri, May 27, 2011 at 7:10 AM, Chris Beeley chris.bee...@gmail.com wrote:
Hello-
I have some code that looks like this:
with(mydatalocal, sum(table(Service[Time==5:8])))
This is designed to add up the numbers of responses between the Time
codes 5 to 8 (which are integers and refer to quarters). Service is
just one of the variables, I'm just trying to count the number of
responses so I picked any of the variables. However, there is
something wrong, it returns far too low a number for the number of
responses. Indeed, if I run this:
with(mydatalocal, sum(table(Service[Time==5|Time==6|Time==7|Time==8])))
I get 4 times as many responses.
I've tried to recreate the problem with the following code:
mydata=data.frame(matrix(c(rep(1, 10), rep(2, 10), rep(3, 10), seq(1,
10, 1), seq(11, 20, 1), seq(21, 30, 1)), ncol=2))
with(mydata, sum(table(X1[X2==9:12])))
with(mydata, sum(table(X1[X2==9|X2==10|X2==11|X2==12])))
but to my immense frustration it actually seems to work fine there,
the same number, 4, both times. However, it does generate the
following error message:
In X2 == 9:12 :
longer object length is not a multiple of shorter object length
I know I can use X1[ Time 9 Time 3] but I would like to know
what is wrong with the 5:8 usage in case I put it somewhere else and
don't notice the problem.
Many thanks!
Chris Beeley
Institute of Mental Health
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--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
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