sapply(lis, function(x) x[which(x == next) + 1])
[1] want1 want2
HTH,
Andy
From: Chris Knight
I am tying myself in knots over subscripts when applied to lists
I have a list along the lines of:
lis-list(c(a,b,next,want1,c),c(d, next, want2, a))
From which I want to extract the
I suggested
sapply(1:length(lis), function (i) {v - lis[[i]]; v[which(v==next)+1]})
Of course that was really dumb. It can be simplified, because the index i
is only used to select a list element, which sapply() wants to do for me
anyway. It should be
sapply(lis,
Chris Knight wrote:
I am tying myself in knots over subscripts when applied to lists
I have a list along the lines of:
lis-list(c(a,b,next,want1,c),c(d, next, want2, a))
From which I want to extract the values following next in each
member of the list, i.e. something along the lines of
Chris Knight [EMAIL PROTECTED] has
lis-list(c(a,b,next,want1,c),c(d, next, want2, a))
and wants c(want1,want2)
Step 1:
inx - sapply(lis, function(x) which(x == next)) + 1
== 4 3
Step 2:
sapply(1:length(lis), function(i) lis[[i]][inx[i]])
== want1 want2
Think
What about ...
unlist(lis)[which(unlist(lis)==next)+1]
[1] want1 want2
... to avoid the loop in sapply?
Richard A. O'Keefe wrote:
Chris Knight [EMAIL PROTECTED] has
lis-list(c(a,b,next,want1,c),c(d, next, want2, a))
and wants c(want1,want2)
Step 1:
inx -
On Tue, 12 Aug 2003, Peter Wolf wrote:
What about ...
unlist(lis)[which(unlist(lis)==next)+1]
[1] want1 want2
... to avoid the loop in sapply?
That has a loop in each unlist, of course. (A slicker version of that
solution was posted earlier by Richard.)
Note that you have to loop
