[R] readr to generate tibble from a character matrix

[Ulrik Stervbo]

Hi Ben,

type.convert should do the trick:

m %>%
  as_tibble() %>%
  lapply(type.convert) %>%
  as_tibble()

I am not too happy about to double 'as_tibble' but it get the job done.

HTH
Ulrik

On Thu, 6 Apr 2017 at 16:41 Ben Tupper <btupper at bigelow.org> wrote:

> Hello,
>
> I have a workflow yields a character matrix that I convert to a tibble.
> Here is a simple example.
>
> library(tibble)
> library(readr)
>
> m <- matrix(c(letters[1:12], 1:4, (11:14 + 0.2)), ncol = 5)
> colnames(m) <- LETTERS[1:5]
>
> x <- as_tibble(m)
>
> # # A tibble: 4 × 5
> #       A     B     C     D     E
> #   <chr> <chr> <chr> <chr> <chr>
> # 1     a     e     i     1  11.2
> # 2     b     f     j     2  12.2
> # 3     c     g     k     3  13.2
> # 4     d     h     l     4  14.2
>
> The workflow output columns can be a mix of a known set column outputs.
> Some of the columns really should be converted to non-character types
> before I proceed.  Right now I explictly set the column classes with
> something like this...
>
> mode(x[['D']]) <- 'integer'
> mode(x[['E']]) <- 'numeric'
>
> # # A tibble: 4 × 5
> #       A     B     C     D     E
> #   <chr> <chr> <chr> <int> <dbl>
> # 1     a     e     i     1  11.2
> # 2     b     f     j     2  12.2
> # 3     c     g     k     3  13.2
> # 4     d     h     l     4  14.2
>
>
> I wonder if there is a way to use the read_* functions in the readr
> package to read the character matrix into a tibble directly which would
> leverage readr's excellent column class guessing. I can see in the vignette
> ( https://cran.r-project.org/web/packages/readr/vignettes/readr.html )
> that I'm not too far off in thinking this could be done (step 1
> tantalizingly says 'The flat file is parsed into a rectangular matrix of
> strings.')
>
> I know that I could either write the matrix to a file or paste it all into
> a character vector and then use read_* functions, but I confess I am
> looking for a straighter path by simply passing the matrix to a function
> like readr::read_matrix() or the like.
>
> Thanks!
> Ben
>
> Ben Tupper
> Bigelow Laboratory for Ocean Sciences
> 60 Bigelow Drive, P.O. Box 380
> East Boothbay, Maine 04544
> http://www.bigelow.org
>
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