I see Joshua has kindly offered some resources to turn you from your
path of erroR and sins against the interpreteR, but if you want to do
extra penance, you might consider reading the R-FAQ (although your
issue if if and "&&" is surprisingly not included there) :
http://cran.r-project.org/doc/FAQ/R-FAQ.html
http://cran.r-project.org/doc/FAQ/R-FAQ.html#R-Miscellanea
Then depending on the level of further contRition you might want to
exert, you could also read the "R Inferno"
(Abstract: If you are using R and you think you’re in hell, this is a
map for you.) by Patrick Burns:
http://www.burns-stat.com/pages/Tutor/R_inferno.pdf (see section 3.2
for your problem)
--
David.
On Sep 16, 2010, at 4:51 PM, George Coyle wrote:
Hello,
I wrote this code which works fine on a single observation:
x<-100
y<-200
z<-125
aa<-150
if(x<z && y>z) {aa-z}
result: 25
I am trying to apply this logic where x,y,z,and aa are arrays but
with very
little success. I have tried using loops and whiles but I always
get errors
of various types. I have consulted a few manuals but with limited
success.
My hopeful outcome would be:
data:
X Y Z AA
1 100 200 125 150
2 125 110 105 140
3 110 150 130 200
4 90 200 75 65
Here row 1 would return 25, row 2 would return nothing since Z<X,
row 3
would be 50, row 4 would be nothing since X>Z.
In this case I am trying to return something where I could call the
output a
variable "Z" which would become an array based on the logic above
where the
members would be: (25, 50)
I tried using this where the variables are arrays:
if(x<z && y>z) {aa-z}
But I get "NULL"
I tried using this where the variables are arrays:
if(x<z && y>z) {aa-z} else "NA"
But I get "NA"
When I tried using a loop:
for(i in 1:length(x)) if(x<z && y>z) {aa-z} else "NA"
I got "NULL"
An attempt at a "while" statement crashed.
The time series resource (
http://cran.r-project.org/doc/contrib/Ricci-refcard-ts.pdf) is way too
involved. Most online sources I am finding are not good for "if"
contingent
array manipulation. Annoyingly, just saying aa-z will work across the
entire array but for some reason my ifs fail. I know the R help
group only
wants serious emails so hopefully this will indicate I gave it a
reasonable shot.
Please help
Thanks
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David Winsemius, MD
West Hartford, CT
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and provide commented, minimal, self-contained, reproducible code.
