On Nov 1, 2008, at 3:30 AM, (Ted Harding) wrote:
On 01-Nov-08 02:51:37, David Winsemius wrote:
Do you want the count of remaining elements which are strictly
greater than the first element?
length(which(a[1] < a[2:10]))
[1] 4
or perhaps a bit more deviously:
sum( a[1]<a[2:10]+0 ) #adding 0 to TRUE or FALSE creates 1 or 0.
[1] 4
No need to be devious! Simply
sum(a[1] < a[2:10])
# [1] 4
will do it. The reason is that when TRUE or FALSE are involved in
an arithmetic operation (which sum() is), they are cast into 1 or 0.
Agreed. I now also see that TRUE+TRUE and T+T both return 2. The
second observation should be further warning to us newbies not to
create variables named "T".
It's now been pointed out to me both on and off list that the +0 is
unnecessary. I don't remember when I learned this, but it could not
have been more than a year ago. I seem to remember that Gabor
Grothendeick used the +0 device to convert a logical vector to a
numeric vector. Perhaps it was for the purpose of making a matrix or
something less necessarily arithmetical than sum() or "+".
--
David Winsemius, MD
Heritage Labs
Ted.
On Oct 31, 2008, at 7:56 PM, sandsky wrote:
Hi there,
I have a data set:
a=cbind(5,2,4,7,8,3,4,11,1,20)
I want to count # of data, satistfying a[1]<a[2:10].
Anyone helps me solving this case?
Thank you in advance,
Jin
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Date: 01-Nov-08 Time: 07:30:17
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