Rtcl

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Rtcl is a [Tcl] extension for executing code in the [R] [http://www.r-project.org]
programming language. R is a free version of Bell Labs' S language for
statistical computing. Rtcl embeds an R interpreter into Tcl, and allows
access to it via Tcl commands. The latest version of Rtcl is available from

https://github.com/mattadams/Rtcl

Rtcl was originally written by [Neil McKay]. His last published version is available from

http://www.eecs.umich.edu/~mckay/computer/Rtcl0.3.tar.gz


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***Installation on macOS***[TR] I have suRtccessfully compileds and uinsed thealls packagerfectly on macOS Catalina (10.15.7), The cusirreng Rtcl version 1.2.1.2 R veralsion 4.0.4 iruns winstallhout thed tweandk lives undescr /Library/Frameworks/R.framd bewlork/Rw (tesourctes.d Thison ismacOS the13.5.2 dirVecntourya returnedning byon an M1 machine).
<<discussion>> Installing Rtcl 1.2.1 on macOS (10.15.7 – Catalina)
I have successfully compiled and used the package on macOS Catalina (10.15.7), using Rtcl version 1.2.1. R version 4.0.4 is installed and lives under /Library/Frameworks/R.framework/Resources. This is the directory returned by

    R RHOME
Compiling Rtcl using just with `./configure; make; make install` works. However, I am getting the error message `cannot load libR` from the Rtcl package when I do `package require Rtcl`. This is because Rtcl cannot find the installed R. First, the `R_HOME` environment variable is not set by R, so the initialization script in Rtcl cannot use it. Second, the paths to R hard-coded into Rtcl do not match my installation, so Rtcl cannot find R at that place either. It doesn't help much to add the correct path in Rtcl's init code. This will help loading the library in Tcl but then R fails with saying `cannot find system Renviron`. It turns out that the easy solution is to just define the `R_HOME` environment variable and set it to the output of `R RHOME`. Depending on your setup, you can just put it into your profile:

    export R_HOME=`R RHOME`

You could also include it into the pkgIndex.tcl file of Rtcl, before the actual libRtcl1.2.1.dylib library is loaded, e.g.:

    set env(R_HOME) [exec /usr/local/bin/R RHOME]
    package ifneeded Rtcl 1.2.1 \
        [list load [file join $dir libRtcl1.2.1.dylib] Rtcl]<<enddiscussion>>

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***Usage***
The package provides four new commands in the rtcl [namespace]:

    ::rtcl::eval ?-verbose? R Expression(s)
    ::rtcl::source ?-verbose? foo.R
    ::rtcl::gettype ?-verbose? R Expression(s)
    ::rtcl::getvalue ?-verbose? R Expression(s)

Here's an example output from the console:
    ======
% package require Rtcl
    1.2.1
    % # the following will just execute some R code without returning anything:
    % ::rtcl::eval "a <- c(1:10)"
    % # if you want to see the content of 'a', you need:
    % ::rtcl::getvalue a
    1 2 3 4 5 6 7 8 9 10
    % # getvalues does also execute the command, so you can do both in one step:
    % ::rtcl::getvalue "a <- c(1:10)"
    1 2 3 4 5 6 7 8 9 10
    % # loading R libraries works as usual:
    % ::rtcl::eval library(sf)
    % we can transfer data to R and get results back like this:
    % set x 5
    % set result [::rtcl::getvalue "$x * $x"]
    % 25.0
    % puts $result
    25.0
    % note, that Rtcl returned a 'real' value:
    % ::rtcl::gettype "$x * $x"
    real
    % ... when doing this in plain R, you will get "25" and 'class(5*5)' will return only 'numeric', so 'real' is the safe choice ...
======

Another example with more complex data, using the built-in dataset 'mtcars':
======
package require Rtcl
1.2.2
% rtcl::eval {data(mtcars)}
% set l [rtcl::getvalue {head(mtcars, 6)}]
{21.0 21.0 22.8 21.4 18.7 18.1} {6.0 6.0 4.0 6.0 8.0 6.0} {160.0 160.0 108.0 258.0 360.0 225.0} {110.0 110.0 93.0 110.0 175.0 105.0} {3.9 3.9 3.85 3.08 3.15 2.76} {2.62 2.875 2.32 3.215 3.44 3.46} {16.46 17.02 18.61 19.44 17.02 20.22} {0.0 0.0 1.0 1.0 0.0 1.0} {1.0 1.0 1.0 0.0 0.0 0.0} {4.0 4.0 4.0 3.0 3.0 3.0} {4.0 4.0 1.0 1.0 2.0 1.0}
% llength $l
11
% lindex $l 1 2
4.0
% rtcl::getvalue {row.names(mtcars)}
{Mazda RX4} {Mazda RX4 Wag} {Datsun 710} {Hornet 4 Drive} {Hornet Sportabout} Valiant {Duster 360} {Merc 240D} {Merc 230} {Merc 280} {Merc 280C} {Merc 450SE} {Merc 450SL} {Merc 450SLC} {Cadillac Fleetwood} {Lincoln Continental} {Chrysler Imperial} {Fiat 128} {Honda Civic} {Toyota Corolla} {Toyota Corona} {Dodge Challenger} {AMC Javelin} {Camaro Z28} {Pontiac Firebird} {Fiat X1-9} {Porsche 914-2} {Lotus Europa} {Ford Pantera L} {Ferrari Dino} {Maserati Bora} {Volvo 142E}
======
This dataset 'mtcars' is an R "data.frame". As you can see, it is returned as a nested list with each element of the list being one column of the dataset. That is why `llength $l` doesn't return 6 (but 11 as the number of columns) when we asked for the first 6 rows. The column headers and row names are not included in the return value. If you need these you can get the column names using `rtcl::getvalue {names(mtcars)}`.





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