[R] Selecting and then joining data blocks

[arun]

In addition,
If your matrix names do not follow any particular pattern:
tiger<- matrix(1:20,ncol=5)
cat<- matrix(21:40,ncol=5)
 dog<- matrix(41:60,ncol=5)
 wolf<- matrix(61:80,ncol=5)
vec<- c(1,2,4,3,2,3,1)
vec2<- c("tiger","cat","dog","wolf")
#Suppose, you wanted the order to be "tiger", "cat", "dog", "wolf"
 vec2<- factor(vec2,levels=vec2) 
 vec2
#[1] tiger cat   dog   wolf 
#Levels: tiger cat dog wolf
 res3<-do.call(rbind,lapply(vec,function(i) get(as.character(vec2[as.numeric(vec2)==i]))))
res3
 #     [,1] [,2] [,3] [,4] [,5]
 #[1,]    1    5    9   13   17
 #[2,]    2    6   10   14   18
 #[3,]    3    7   11   15   19
 #[4,]    4    8   12   16   20
 #[5,]   21   25   29   33   37
 #[6,]   22   26   30   34   38
 #[7,]   23   27   31   35   39
 #[8,]   24   28   32   36   40
 #[9,]   61   65   69   73   77
#[10,]   62   66   70   74   78
#[11,]   63   67   71   75   79
#[12,]   64   68   72   76   80
#[13,]   41   45   49   53   57
#[14,]   42   46   50   54   58
#[15,]   43   47   51   55   59
#[16,]   44   48   52   56   60
#[17,]   21   25   29   33   37
#[18,]   22   26   30   34   38
#[19,]   23   27   31   35   39
#[20,]   24   28   32   36   40
#[21,]   41   45   49   53   57
#[22,]   42   46   50   54   58
#[23,]   43   47   51   55   59
#[24,]   44   48   52   56   60
#[25,]    1    5    9   13   17
#[26,]    2    6   10   14   18
#[27,]    3    7   11   15   19
#[28,]    4    8   12   16   20

A.K.





----- Original Message -----
From: arun <smartpink111 at yahoo.com>
To: Preetam Pal <lordpreetam at gmail.com>
Cc: 
Sent: Thursday, April 25, 2013 9:03 AM
Subject: Re: [R] Selecting and then joining data blocks

HI Preetam,

I created the matrices in a list because it was easier to create.  If you look at the second solution:


B1<- lst1[[1]]
 B2<- lst1[[2]]
 B3<- lst1[[3]]
 B4<- lst1[[4]]

Consider that B1, B2, B3, B4 are your actual matrices and apply the solution below:

 paste0("B",vec) #gives the names of the matrices
#[1] "B1" "B2" "B4" "B3" "B2" "B3" "B1"
using get(), will get the matrices stored in that names.

 res2<-do.call(rbind,lapply(vec,function(i) get(paste0("B",i))))


If the names of the matrices are different, you need to change it accordingly.  I programmed it based on the information you gave.

I hope this helps.
Arun


________________________________
From: Preetam Pal <lordpreetam at gmail.com>
To: arun <smartpink111 at yahoo.com> 
Sent: Thursday, April 25, 2013 8:53 AM
Subject: Re: [R] Selecting and then joining data blocks



Hi Arun,



Thanks for your solution. But there is only 1  thing which i could not understand:

In my case, the 4 matirces(B1,B2,B3,B4) were already specified and i have to work with these only...how do I accommodate that (instead of letting R produce the big matrix by random sampling)..This might be very trivial, but i am a starter with R...I shall really appreciate if you could advise me on this.

Again thanks,
Preetam



On Thu, Apr 25, 2013 at 5:44 PM, arun <smartpink111 at yahoo.com> wrote:

HI,
>set.seed(24)
>#creating the four matrix in a list
>
>lst1<-lapply(1:4,function(x) matrix(sample(1:40,20,replace=TRUE),ncol=5))
>names(lst1)<- paste0("B",1:4)
>vec<- c(1,2,4,3,2,3,1)
>res<-do.call(rbind,lapply(vec,function(i) lst1[[i]]))
>dim(res)
>#[1] 28  5
>
>
>#or
>B1<- lst1[[1]]
> B2<- lst1[[2]]
> B3<- lst1[[3]]
> B4<- lst1[[4]]
>
> res2<-do.call(rbind,lapply(vec,function(i) get(paste0("B",i))))
> identical(res,res2)
>#[1] TRUE
>A.K.
>
>
>
>
>
>----- Original Message -----
>From: Preetam Pal <lordpreetam at gmail.com>
>To: r-help at r-project.org
>Cc:
>Sent: Thursday, April 25, 2013 7:51 AM
>Subject: [R] Selecting and then joining data blocks
>
>Hi all,
>
>I have 4 matrices, each having  5 columns and 4 rows .....denoted by
>B1,B2,B3,B4.
>I have generated a vector of 7 indices, say (1,2,4,3,2,3,1} which refers to
>the index of the matrices to be chosen and then appended one on the top of
>the next: like, in this case, I wish to have the following mega matrix:
>B1over B2 over B4 over B3 over B2 over B3 over B1.
>
>1> How can I achieve this?
>2> I don't want to manually identify and arrange the matrices for each
>vector of index values generated   (for which the code  I used is :
>index=sample( 4,7,replace=T)). How can I automate the process?
>
>Basically, I am doing bootstrapping , but the observations are actually 4X5
>matrices.
>
>Appreciate your help.
>
>
>Thanks,
>Preetam
>
>
>---
>
>Preetam Pal
>(+91)-9432212774
>M-Stat 2nd Year,                                             Room No. N-114
>Statistics Division,                                           C.V.Raman
>Hall
>Indian Statistical Institute,                                 B.H.O.S.
>Kolkata.
>
>    [[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.
>
>


-- 
Preetam Pal                                                   (+91)-9432212774
M-Stat 2nd Year,                                             Room No. N-114
Statistics Division,                                           C.V.Raman Hall
Indian Statistical Institute,                                 B.H.O.S.
Kolkata.