> On Nov 30, 2017, at 6:27 AM, Martin Møller Skarbiniks Pedersen
> <traxpla...@gmail.com> wrote:
>
> Hi,
> I think and hope this a good place to ask for code review for a R
> beginners?
>
> I have made a R script which generates a dataset based on 2009 danish
> referendum and it does work.
>
> But I think the code could be better and I would any comments how the
> code can be improved.
> At least I would like to know how I avoid converting several of the
> columns to factors in the end of the code?
>
> Description of the code:
>
> It reads a lot of xml-files from ../raw/ and saves a data.frame with
> information
> from these xml-files.
>
> In the ../raw/ directiory I have placed the xml-files which I got from
> "Statistics Denmark"
> I have also put these xml-files on my website and they can be download
> freely from http://20dage.dk/R/referendum-2009/raw.tar.gz
>
> The code is below but I have also put the code at this place:
> http://20dage.dk/R/referendum-2009/convert_from_xml.R
>
> Best Regards
> Martin M. S. Pedersen
>
> -------
> library(xml2)
>
> convert_one_file <- function(url) {
> x <- read_xml(url)
>
> Sted <- xml_find_first(x, ".//Sted")
> StedType <- xml_attr(Sted, "Type")
> StedTekst <- xml_text(Sted)
>
> Parti <- xml_find_all(x, ".//Parti")
> PartiId <- xml_attr(Parti, "Id")
> PartiBogstav <- xml_attr(Parti, "Bogstav")
> PartiNavn <- xml_attr(Parti, "Navn")
>
>
> StemmerAntal <- xml_attr(Parti, "StemmerAntal")
> Stemmeberettigede <- xml_integer(xml_find_first(x,
> ".//Stemmeberettigede"))
> DeltagelsePct <- xml_double(xml_find_first(x, ".//DeltagelsePct"))
> IAltGyldigeStemmer <- xml_integer(xml_find_first(x,
> ".//IAltGyldigeStemmer"))
> BlankeStemmer <- xml_integer(xml_find_first(x, ".//BlankeStemmer"))
> AndreUgyldigeStemmer <- xml_integer(xml_find_first(x,
> ".//AndreUgyldigeStemmer"))
>
> data.frame(cbind(StedType, StedTekst, PartiId, PartiBogstav, PartiNavn,
> StemmerAntal, Stemmeberettigede, DeltagelsePct,
> IAltGyldigeStemmer,
> BlankeStemmer, AndreUgyldigeStemmer), stringsAsFactors = FALSE)
The construction `data.frame(cbind( ...` is a serious source of potential
error. The cbind coerces to matrix class which also then coerces to a single
atomic class, either numeric or character. Factors loose all their meaning.
Dates get messed up. Error ensues. Better would be:
data.frame( StedType, StedTekst, PartiId, PartiBogstav, PartiNavn,
StemmerAntal, Stemmeberettigede, DeltagelsePct,
IAltGyldigeStemmer, BlankeStemmer, AndreUgyldigeStemmer,
stringsAsFactors = FALSE)
--
David.
> }
>
> raw_path <- "../raw"
> filenames <- dir(path = raw_path, pattern = "fintal_.*", full.names = T)
>
> result <- data.frame(StedType = factor(),
> StedTekst = character(),
> PartiId = factor(),
> PartiBogstav = factor(),
> PartiNavn = factor(),
> StemmerAntal = integer(),
> Stemmeberettigede = integer(),
> DeltagelsePct = numeric(),
> IAltGyldigeStemmer = integer(),
> BlankeStemmer = integer(),
> AndreUgyldigeStemmer = integer(),
> stringsAsFactors = FALSE)
>
> for (i in 1:length(filenames)) {
> #cat(paste0(filenames[i],"\n"))
> returnCode <- tryCatch({
> result <- rbind(result, convert_one_file(filenames[i]))
> }, error = function(e) {
> cat(paste0(filenames[i]," failed:\n",e,"\n"))
> })
> }
>
> result$StedType <- as.factor(result$StedType)
> result$PartiId <- as.factor(result$PartiId)
> result$PartiBogstav <- as.factor(result$PartiBogstav)
> result$PartiNavn <- as.factor(result$PartiNavn)
> result$StemmerAntal <- as.integer(result$StemmerAntal)
> result$Stemmeberettigede <- as.integer(result$Stemmeberettigede)
> result$DeltagelsePct <- as.numeric(result$DeltagelsePct)
> result$IAltGyldigeStemmer <- as.integer(result$IAltGyldigeStemmer)
> result$BlankeStemmer <- as.integer(result$BlankeStemmer)
> result$AndreUgyldigeStemmer <- as.integer(result$AndreUgyldigeStemmer)
> str(result)
> save(result, file = "folkeafstemning2009.Rdata")
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
David Winsemius
Alameda, CA, USA
'Any technology distinguishable from magic is insufficiently advanced.'
-Gehm's Corollary to Clarke's Third Law
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