R help - Apr 2012 - return one vector that is the sum of a list of vectors

Dear R Help,

I am attempting to write a function that  takes a list of variable groups and a
vector of numbers (e.g., "jtsv" would indicate one group of variables,
"jtsv1", "jtsv2", etc, each of which name a variable in a
data frame), and returns a list of variable group sums. For example, given
list("jtsv", "ptsv") and c(1:10), where jtsv1, etc, are all
numeric vectors of the same length, the function should return a list of jtsv
and ptsv, where
jtsv <- jtsv1 + jtsv2 + jtsv3 + jtsv4 + jtsv5 + jtsv6 + jtsv7 + jtsv8 + jtsv9
+ jtsv10
ptsv <- ptsv1 + ptsv2 + ptsv3 + ptsv4 + ptsv5 + ptsv6 + ptsv7 + ptsv8 + ptsv9
+ ptsv10

So far I've used a for loop to paste together the names of the variables as
character vectors, so that I can at least name the variables that I want to get,
but I'm stuck on how to add together the numeric vectors that those
character vectors are ultimately supposed to name. It seems like I should be
able to map the primitive "+" operator onto a list or vector that
contains the variable names. If that's a good way to go, what would that
look like? Or if that's not a good way to go, would someone please point me
in a good direction?

Sincerely,
Frank Tamborello



	[[alternative HTML version deleted]]

?get
?rowSums
?rowsum

a "group" is not a defined data structure in R, btw. You have a much
better chance of getting precise answers if you ask precise questions.
See  the Posting Guide.

-- Bert

On Sun, Apr 8, 2012 at 9:01 PM, Frank Tamborello <frank.tambo at
gmail.com> wrote:
> Dear R Help,
>
> I am attempting to write a function that ?takes a list of variable groups
and a vector of numbers (e.g., "jtsv" would indicate one group of
variables, "jtsv1", "jtsv2", etc, each of which name a
variable in a data frame), and returns a list of variable group sums. For
example, given list("jtsv", "ptsv") and c(1:10), where
jtsv1, etc, are all numeric vectors of the same length, the function should
return a list of jtsv and ptsv, where
> jtsv <- jtsv1 + jtsv2 + jtsv3 + jtsv4 + jtsv5 + jtsv6 + jtsv7 + jtsv8 +
jtsv9 + jtsv10
> ptsv <- ptsv1 + ptsv2 + ptsv3 + ptsv4 + ptsv5 + ptsv6 + ptsv7 + ptsv8 +
ptsv9 + ptsv10
>
> So far I've used a for loop to paste together the names of the
variables as character vectors, so that I can at least name the variables that I
want to get, but I'm stuck on how to add together the numeric vectors that
those character vectors are ultimately supposed to name. It seems like I should
be able to map the primitive "+" operator onto a list or vector that
contains the variable names. If that's a good way to go, what would that
look like? Or if that's not a good way to go, would someone please point me
in a good direction?
>
> Sincerely,
> Frank Tamborello
>
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


-- 

Bert Gunter
Genentech Nonclinical Biostatistics

Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm

On Apr 9, 2012, at 12:01 AM, Frank Tamborello wrote:
> Dear R Help,
>
> I am attempting to write a function that  takes a list of variable  
> groups and a vector of numbers (e.g., "jtsv" would indicate one  
> group of variables, "jtsv1", "jtsv2", etc, each of
which name a
> variable in a data frame), and returns a list of variable group  
> sums. For example, given list("jtsv", "ptsv") and
c(1:10), where
> jtsv1, etc, are all numeric vectors of the same length, the function  
> should return a list of jtsv and ptsv, where
> jtsv <- jtsv1 + jtsv2 + jtsv3 + jtsv4 + jtsv5 + jtsv6 + jtsv7 +  
> jtsv8 + jtsv9 + jtsv10
> ptsv <- ptsv1 + ptsv2 + ptsv3 + ptsv4 + ptsv5 + ptsv6 + ptsv7 +  
> ptsv8 + ptsv9 + ptsv10
>
> So far I've used a for loop to paste together the names of the  
> variables as character vectors, so that I can at least name the  
> variables that I want to get, but I'm stuck on how to add together  
> the numeric vectors that those character vectors are ultimately  
> supposed to name. It seems like I should be able to map the  
> primitive "+" operator onto a list or vector that contains the  
> variable names. If that's a good way to go, what would that look  
> like? Or if that's not a good way to go, would someone please point  
> me in a good direction?
>
Perhaps (.... depending on detail not provided):

jtsv <- rowSums( dfrm[ , grep("jtsv", names(dfrm))] )

-- 

David Winsemius, MD
West Hartford, CT