Hi,

Much better! That seems to work great. The only time it doesn't work is that if 
all the elements are NA for a specific element. Then it gives me a numeric(0) 
for that cell rather than NA.

On Sep 21, 2010, at 2:30 PM, Henrique Dallazuanna wrote:

> Try this:
> 
>  apply(array(unlist(mymats), dim = c(dim(mymats[[1]]), length(mymats))), 1:2, 
> mode)
> 
> The error was in c(length(mymats), dim(mymats[[1]]))
> 
> On Tue, Sep 21, 2010 at 3:19 PM, Gregory Ryslik <rsa...@comcast.net> wrote:
> Ack,  apologies for the previous email. What I meant to say is that the first 
> element is calculated incorrectly (1,1) should be 2, instead it is 3. I've 
> been staring at the code for two long. I've copied it in again for 
> convenience.
> 
> mymats <- vector('list', 4)
> set.seed(246)
> 
> # Generate a list of 4 3 x 3 matrices
> for(i in 1:4) mymats[[i]] <- matrix(sample(1:9), nrow = 3)
> 
> mymats[[1]][1,1]<-3
> mymats[[1]][1,2]<-3
> mymats[[1]][1,3]<-1
> mymats[[2]][2,1]<-2
> mymats[[1]][2,2]<-3
> mymats[[1]][2,3]<-1
> mymats[[1]][3,1]<-2
> mymats[[1]][3,2]<-2
> mymats[[1]][3,3]<-3
> 
> mymats[[2]][1,1]<-2
> mymats[[2]][1,2]<-3
> mymats[[2]][1,3]<-2
> mymats[[2]][2,1]<-1
> mymats[[2]][2,2]<-2
> mymats[[2]][2,3]<-2
> mymats[[2]][3,1]<-1
> mymats[[2]][3,2]<-3
> mymats[[2]][3,3]<-2
> 
> mymats[[3]][1,1]<-NA
> mymats[[3]][1,2]<-2
> mymats[[3]][1,3]<-2
> mymats[[3]][2,1]<-2
> mymats[[3]][2,2]<-3
> mymats[[3]][2,3]<-1
> mymats[[3]][3,1]<-2
> mymats[[3]][3,2]<-2
> mymats[[3]][3,3]<-3
> 
> mymats[[4]][1,1]<-2
> mymats[[4]][1,2]<-1
> mymats[[4]][1,3]<-2
> mymats[[4]][2,1]<-3
> mymats[[4]][2,2]<-2
> mymats[[4]][2,3]<-3
> mymats[[4]][3,1]<-1
> mymats[[4]][3,2]<-2
> mymats[[4]][3,3]<-1
> 
> mymats
> 
> 
> mode <- function(x){
>       as.numeric(names(which.max(table(x)))) 
>       }
> apply(array(unlist(mymats), dim = c(length(mymats), dim(mymats[[1]]))), 1:2, 
> mode)
> 
> 
> On Sep 21, 2010, at 10:08 AM, Henrique Dallazuanna wrote:
> 
>> Try this:
>> 
>> mode <- function(x, ...)
>>     as.numeric(names(which.max(table(x))))
>> apply(array(unlist(mymats), dim = c(length(mymats), dim(mymats[[1]]))), 1:2, 
>> mode)
>> 
>> 
>> On Tue, Sep 21, 2010 at 10:47 AM, Gregory Ryslik <rsa...@comcast.net> wrote:
>> Hi Everyone,
>> 
>> I am interested in taking the mode over several thousand matrices. I show an 
>> example below. For the [1,1] entry of my "mode" matrix that I want to create 
>> I would like to have a "2". For the [1,2] entry I would want a 2.  For the 
>> [2,2] entry it would be 4 and so forth. Earlier, I was working with 
>> continuous cases and thus each (n,m) element was simply an average. I was 
>> able to then do element-wise addition and counting using the "Reduce" 
>> function and then the average would be totalsum/totalcount where the NA 
>> terms were discounted. Here, it's not exactly a binary case so Reduce 
>> doesn't quite work as well. I'm open to suggestions but would as always like 
>> to avoid long loops as that will significantly bump up running time over 
>> several thousand trees. Similarly, I would not like to do a lot of sorts to 
>> find the mode either...
>> 
>> Thanks for your help!
>> 
>> mymats
>> [[1]]
>>     [,1] [,2] [,3]
>> [1,]    0    2    1
>> [2,]    2    3    3
>> [3,]    2    1    2
>> 
>> [[2]]
>>     [,1] [,2] [,3]
>> [1,]    1    2    4
>> [2,]    2    4    4
>> [3,]    3    4    5
>> 
>> [[3]]
>>     [,1] [,2] [,3]
>> [1,]    2    3    1
>> [2,]    3    4    2
>> [3,]    5    1    3
>> 
>> [[4]]
>>     [,1] [,2] [,3]
>> [1,]    2    4    2
>> [2,]    1   NA    2
>> [3,]    2    3    1
>> 
>> [[5]]
>>     [,1] [,2] [,3]
>> [1,]   NA    2    1
>> [2,]    2    4    1
>> [3,]    1    3    2
>> ______________________________________________
>> R-help@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.
>> 
>> 
>> 
>> -- 
>> Henrique Dallazuanna
>> Curitiba-Paraná-Brasil
>> 25° 25' 40" S 49° 16' 22" O
> 
> 
> 
> 
> -- 
> Henrique Dallazuanna
> Curitiba-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O


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