How to convert a single string array in to multiple variables

Question

Since I cannot convert a given data file to anything useful such as a .csv file, I want to extract multiple variables from a single string.

A string is labeled as A and has X points (somewhere between 10 and 17). The first point corresponds to 1 (as in A1) and the second to A2, et cetera. If there are only 10 numbers then max would be A10, if there are 17 then A17 is the max. I am not sure how to use dim().

How do I chronologically extract the numbers from my single string variable A in to multiple variables that are numbered A1:5 if there are 5 numbers in a given string?

A: 0.00 15.00 16.00 0.00 12.00

into

id   A1    A2     A3     A4    A5
001  0.00  15.00  16.00  0.00  12.00

Allan Cameron · Accepted Answer · 2022-12-08 12:19:25Z

1

If your string is called string:

string <- "A: 0.00 15.00 16.00 0.00 12.00"

Then you could do something like:

sub(":", "", string) |>
  strsplit(' ') |>
  sapply(function(x) {
    setNames(as.numeric(x[-1]), paste0(x[1], seq_along(x[-1])))
  }) |> 
  t() |>
  as.data.frame()
#>   A1 A2 A3 A4 A5
#> 1  0 15 16  0 12

answered Dec 8, 2022 at 12:19

Allan Cameron

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3 Comments

fleems Over a year ago

Thank you! It works with some fiddling around, I still had to change some vars. Some are apparently numeric and some a strings (or character vars). This dataset is horrible. Could you show how to extract the result from a numeric variable? I have a lot of variables that require this procedure

Allan Cameron Over a year ago

@fleems the above answer is numeric. (It's a data frame with numeric columns). What do you mean by "extract the result"? In what format?

fleems Over a year ago

I meant if the starting variable wasn't a string, but a numeric array of numbers (as in a data frame). So from a original numeric variable, that has 5 data points, extract the A1 to A5 variables chronologically.

akrun · Accepted Answer · 2022-12-08 16:42:58Z

1

Another option with read.table

out <- read.table(text = trimws(string, whitespace = ".*:\\s+"), header = FALSE)
names(out) <- sub("V", substring(string, 1, 1), names(out))

-output

> out
  A1 A2 A3 A4 A5
1  0 15 16  0 12

data

string <- "A: 0.00 15.00 16.00 0.00 12.00"

answered Dec 8, 2022 at 16:42

akrun

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