How to convert a vector of strings to a dataframe or matrix
r
Solution
You can use `strsplit`. For example (assuming your vector is an object named `x`):
y <- strsplit(x,"")
z <- lapply(y, as.numeric)
a <- do.call(rbind, z)
This will be faster than the above solution, but is less intuitive. `sapply` simplifies to an array, but you have to transpose it because the dimensions are opposite of what you want.
a <- t(sapply(y, as.numeric))
Here's a comparison of the timings of the different methods proposed in the answers (so far):
x <- sample(c("111","1 1"," 1","112","121","11 "," ","221"), 1e5, TRUE)
f1 <- function(x) do.call(rbind, lapply(strsplit(x,""), as.numeric))
f2 <- function(x) t(sapply(strsplit(x,""), as.numeric))
f3 <- function(x) read.fwf(file=textConnection(x), widths=c(1,1,1))
library(rbenchmark)
benchmark(f1(x), f2(x), f3(x), replications=10, order="relative",
columns=c("test","replications","elapsed","relative"))
# test replications elapsed relative
# 2 f2(x) 10 5.072 1.000000
# 1 f1(x) 10 6.343 1.250591
# 3 f3(x) 10 119.892 23.638013
Problem
I have a vector of n-length strings of numerals that looks like this (in this case, n=3): ``` [1] "111" "111" "111" "111" "111" "111" "111" "111" "111" "111" "111" "111" [13] "111" "111" "111" "111" "111" "111" "111" "111" "111" "111" "111" "111" [25] "111" "111" "111" "111" "111" "111" "111" "1 1" "111" " 1" "111" "112" [37] "121" "111" "111" "111" "11 " "111" " " "111" "111" "221" "111" "111" [49] " " "111" "111" ``` I want to convert it into a matrix (or dataframe) that looks like this: ``` V1 V2 V3 1 1 1 1 1 1 1 1 1 ... 1 NA 1 1 1 1 NA NA 1 ``` etc. I know I can do it in a doubly-nested loop with substring() and as.numeric(), but there must be a more R-like way to accomplish this. Can anyone offer a clue? TIA.