How to parse INI like configuration files with R? - r

Question

Is there an R function for parsing INI like configuration files?
While searching I only found this discussion.

Answer 1

Here is an answer that was given to exact the same question on r-help in 2007 (thanks to #Spacedman for pointing this out):
Parse.INI <- function(INI.filename)
{
connection <- file(INI.filename)
Lines <- readLines(connection)
close(connection)
Lines <- chartr("[]", "==", Lines) # change section headers
connection <- textConnection(Lines)
d <- read.table(connection, as.is = TRUE, sep = "=", fill = TRUE)
close(connection)
L <- d$V1 == "" # location of section breaks
d <- subset(transform(d, V3 = V2[which(L)[cumsum(L)]])[1:3],
V1 != "")
ToParse <- paste("INI.list$", d$V3, "$", d$V1, " <- '",
d$V2, "'", sep="")
INI.list <- list()
eval(parse(text=ToParse))
return(INI.list)
}
Actually, I wrote a short and presumably buggy function (i.e. not covering all corner cases) which works for me now:
read.ini <- function(x) {
if(length(x)==1 && !any(grepl("\\n", x))) lines <- readLines(x) else lines <- x
lines <- strsplit(lines, "\n", fixed=TRUE)[[1]]
lines <- lines[!grepl("^;", lines) & nchar(lines) >= 2] # strip comments & blank lines
lines <- gsub("\\r$", "", lines)
idx <- which(grepl("^\\[.+\\]$", lines))
if(idx[[1]] != 1) stop("invalid INI file. Must start with a section.")
res <- list()
fun <- function(from, to) {
tups <- strsplit(lines[(from+1):(to-1)], "[ ]*=[ ]*")
for (i in 1:length(tups))
if(length(tups[[i]])>2) tups[[i]] <- c(tups[[i]][[1]], gsub("\\=", "=", paste(tail(tups[[i]],-1), collapse="=")))
tups <- unlist(tups)
keys <- strcap(tups[seq(from=1, by=2, length.out=length(tups)/2)])
vals <- tups[seq(from=2, by=2, length.out=length(tups)/2)]
sec <- strcap(substring(lines[[from]], 2, nchar(lines[[from]])-1))
res[[sec]] <<- setNames(vals, keys)
}
mapply(fun, idx, c(tail(idx, -1), length(lines)+1))
return(res)
}
where strcap is a helper function that capitalizes a string:
strcap <- function(s) paste(toupper(substr(s,1,1)), tolower(substring(s,2)), sep="")
There are also some C solutions for this, like inih or libini that might be useful. I did not try them out, though.