Andrew Piskorski
2014-Apr-21 19:28 UTC
[Rd] how to get old type.convert() numeric behavior?
Regarding this change:> CHANGES IN R 3.1.0: > NEW FEATURES: > * type.convert() (and hence by default read.table()) returns a > character vector or factor when representing a numeric input as a > double would lose accuracy. Similarly for complex inputs. > > If a file contains numeric data with unrepresentable numbers of > decimal places that are intended to be read as numeric, specify > colClasses in read.table() to be "numeric".How do I get the old behavior where type.convert() automatically converts to numeric if suitable, regardless of whether or not the string has more than 17 digits of accuracy? Sure, I could first pass every single column of data through a kludgy checking function like my.can.be.numeric() below, and then set colClasses to "numeric" or not based on that, but is there a better way? my.can.be.numeric <- function(xx) { old.warn <- options(warn = -1) on.exit(options(old.warn)) (!is.na(as.numeric(xx))) } Example of the changed behavior in R 3.1.0 vs. earlier versions, both with options("digits"=10) set: # R version 3.1.0 Patched (2014-04-15 r65398) -- "Spring Dance" # Platform: x86_64-unknown-linux-gnu/x86_64 (64-bit)> type.convert(paste("0.", paste(rep(0:9,3)[seq_len(17)],collapse=""), sep=""), as.is=TRUE)[1] 0.01234568> type.convert(paste("0.", paste(rep(0:9,3)[seq_len(18)],collapse=""), sep=""), as.is=TRUE)[1] "0.012345678901234567" # R version 3.0.2 Patched (2013-10-23 r64103) -- "Frisbee Sailing" # Platform: x86_64-unknown-linux-gnu/x86_64 (64-bit)> type.convert(paste("0.", paste(rep(0:9,3)[seq_len(17)],collapse=""), sep=""), as.is=TRUE)[1] 0.01234568> type.convert(paste("0.", paste(rep(0:9,3)[seq_len(18)],collapse=""), sep=""), as.is=TRUE)[1] 0.01234568 -- Andrew Piskorski <atp at piskorski.com>