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 <lordpree...@gmail.com>
To: r-help@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.
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