On Sep 22, 2009, at 5:52 AM, Juliane Struve wrote:
Dear Jim and Henrique,
thank you both for your help. I have done this but run into another
problem:
In the example below "loc1,loc2" occurs in the (now correct, thanks
to your advice) "list" twice.
trips=("loc1,loc2","loc2,loc3")
DF$listoftrips=("loc1,loc2", "loc1,loc3", "loc2,loc3","loc1,loc2").
Not a working example:
> DF <-data.frame(listoftrips=c("loc1,loc2", "loc1,loc3",
"loc2,loc3","loc1,loc2"))
> trips=c("loc1,loc2","loc2,loc3")
>
> DF$listoftrips %in% trips
[1] TRUE FALSE TRUE TRUE
> DF[DF$listoftrips %in% trips, ]
[1] loc1,loc2 loc2,loc3 loc1,loc2
Levels: loc1,loc2 loc1,loc3 loc2,loc3
I am now using
DF$Data[match(trips,listoftrips)] to get Data associated with the
trips listed in "trips".
My problem is that multiple matches occur and match() seems to yield
only the first match. I am interested in all matches per trip and
actually would like to find the mean of DF$Data associated with each
trip listed in "trips".
I have searched the help files and believe that the solution is
aggregate() rather than match(), but I haven't quite figured out how
to apply it for this example.
mean(DF$Data[match(trips,listoftrips)]) gives the mean for all
trips, so that's not right. How can I get means for all trips in
"trips" ???
Many thanks for any suggestions.
----- Original Message ----
From: jim holtman <[email protected]>
To: Juliane Struve <[email protected]>
Cc: [email protected]
Sent: Friday, 18 September, 2009 15:02:47
Subject: Re: [R] matching pairs regardless of order
Here is an example:
x <- c('loc1,loc2', 'loc2,loc3', 'loc2,loc1', 'loc3,loc1')
x.s <- strsplit(x, ',')
# now sort them
x.s <- sapply(x.s, sort)
# create new output
unique(apply(x.s, 2, paste, collapse=','))
[1] "loc1,loc2" "loc2,loc3" "loc1,loc3"
On Fri, Sep 18, 2009 at 8:47 AM, Juliane Struve
<[email protected]> wrote:
Dear list,
I am using match() to match pairs of locations, e.g.
trip="loc1,loc2" from a list of such pairs, e.g. list=("loc1,loc2",
"loc1,loc3", "loc2,loc3","loc2,loc1").
In this example match() will match "trip" with the first element of
"list", but not the 4th, because the order is reversed.
How can I get a match with both ?
Many thanks for any help,
Juliane
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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