converting some rows into columns in R - regex

Question

I have a table with 1 columns and I want to extract one among the other elements in rows and insert into new column.
lets say my table: df
V1
elements-of-01-to-20
ACTCTGCGACHCHAHAATT
elements-of-21-to-30
ACTAGCTATTATCGATATT
elements-of-31-to-40
CCCTTATATTGGAGCTACT
my desired result:
V1 V2
elements-of-01-to-20 ACTCTGCGACHCHAHAATT
elements-of-21-to-20 ACTAGCTATTATCGATATT
elements-of-31-to-20 CCCTTATATTGGAGCTACT
elements-of-31-to-40 CCCTTATATTGGAGCTACT
edited:
thanks for all replies. my second question is what if my dataset has multiple sequences followed by specific term like elements-of:
V1 => result => V1 v2
elements-of-01-to-20 elements-of-01-to-20 ACTCTGCGACHCHAHAATTAGGGGATGCTGATTTAGTA
ACTCTGCGACHCHAHAATT elements-of-21-to-30 ACTAGCTATTATCGATATT
AGGGGATGCTGATTTAGTA
elements-of-21-to-30
ACTAGCTATTATCGATATT

Answer 1

If the pattern is the same as in the example
indx <- c(TRUE, FALSE)
data.frame(V1=df$V1[indx], V2=df$V1[!indx])
# V1 V2
#1 elements-of-01-to-20 ACTCTGCGACHCHAHAATT
#2 elements-of-21-to-30 ACTAGCTATTATCGATATT
#3 elements-of-31-to-40 CCCTTATATTGGAGCTACT
Update
Based on the updated dataset
library(data.table)
setDT(df)[,list(V1=V1[1], V2=paste(V1[-1], collapse='')),
by= list(indx=cumsum(grepl('^[^A-Z]', df$V1)))][, indx:=NULL][]
# V1 V2
#1: elements-of-01-to-20 ACTCTGCGACHCHAHAATTAGGGGATGCTGATTTAGTA
#2: elements-of-21-to-30 ACTAGCTATTATCGATATT
New data
df <- structure(list(V1 = c("elements-of-01-to-20", "ACTCTGCGACHCHAHAATT",
"AGGGGATGCTGATTTAGTA", "elements-of-21-to-30", "ACTAGCTATTATCGATATT"
)), .Names = "V1", class = "data.frame", row.names = c(NA, -5L))

Answer 2

If that is just a fasta file then look at the Biostrings package. You could do it this way too
MySeq <- data.frame("Name" = df$V1[(seq(1, length(df$V1), by=2)],
"Seq" = df$V1[(seq(2, length(df$V1), by=2)],
stringsAsFactors = FALSE)

Answer 3

Here is another way using grepl:
#dummy data
df <- read.table(text=" V1
elements-of-01-to-20
ACTCTGCGACHCHAHAATT
elements-of-21-to-30
ACTAGCTATTATCGATATT
elements-of-31-to-40
CCCTTATATTGGAGCTACT",
as.is=TRUE,header=TRUE)
#result
cbind(df[ grepl("elements",df$V1), "V1"],
df[ !grepl("elements",df$V1), "V1"])
#output
# [,1] [,2]
# [1,] "elements-of-01-to-20" "ACTCTGCGACHCHAHAATT"
# [2,] "elements-of-21-to-30" "ACTAGCTATTATCGATATT"
# [3,] "elements-of-31-to-40" "CCCTTATATTGGAGCTACT"

Answer 4

Try (using traditional programming methods):
ndf = data.frame(V1="", V2="", stringsAsFactors=FALSE)
i=1
while(i<nrow(df)){
ndf[(nrow(ndf)+1),]=c(df[i,1], df[(i+1),1])
i=i+2
}
ndf[-1,]
V1 V2
2 elements-of-01-to-20 ACTCTGCGACHCHAHAATT
3 elements-of-21-to-30 ACTAGCTATTATCGATATT
4 elements-of-31-to-40 CCCTTATATTGGAGCTACT