[R] scan or source a text file into a list

[Andy Bunn]

I've ported somebody else's rather cumbersome Matlab model to R for
colleagues that want a free build of the model with the same type of I/O.

The Matlab model reads a text file with the initial parameters specified as:

C:\Data\Carluc\Rport>more Params.R
# Number of years to simulate
nYears = 50;
# Initial year for graphing purposes
year0 = 1970;
# NPP/GPP ratio (cpp0 unitless)
fnr = 0.30;
# Quantum efficency
qe  = 0.040;

That is, there are four input variables (for this run - there can be many
more) written in a way that R can understand them. In R, I can have the
model source the parameter text file easily enough and have the objects in
the workspace. The model function in R takes a list at runtime. How can I
have R read that file and put the contents into the list I need?

E.g.,
> rm(list = ls())
> source("Params.R")
> ls()
[1] "fnr"    "nYears" "qe"     "year0"
> fnr
[1] 0.3
> nYears
[1] 50
> foo.list <- list(fnr = fnr, nYears = nYears)
>
> foo.list
$fnr
[1] 0.3

$nYears
[1] 50


The model is then run with
> CarlucR(inputParamList = foo.list, ...)

I can't build inputParamList "by hand" as above because the number of
initial parameters changes with the model run and this runs in a wrapper.

Any thoughts? Some combination of paste with scan or parse?
-Andy


> version
         _
platform i386-pc-mingw32
arch     i386
os       mingw32
system   i386, mingw32
status
major    2
minor    0.0
year     2004
month    10
day      04
language R
>