undesirable rounding off due to 'read.table' (PR#8974)

Full_Name: Aart Overeem
Version: 2.2.0

You are asked not to report bugs on out-dated versions of R...

OS: Linux
Submission from: (NULL) (145.23.254.155)


Construct a dataframe consisting of several variables by using 'data.frame' and
'cbind' and write it to a file with 'write.table'. The file consists of headers
and values, such as 12.4283675334551 (so 13 numbers behind the decimal point).
If this dataframe is read with 'read.table(filename, skip = 1)' or
'read.table(filename, header = TRUE') the values only have 7 numbers behind the
decimal point, e.g. 12.42837. So, the reading rounds off the values. This is not
mentioned in the manual. Although the values still have many numbers behind the
decimal point, rounding off is, in my view, never desirable.

Works for me in R 2.3.1 (patched)

Are you mistaking the printed representation of your data.frame for the
real thing. E.g.:

# dummy data
dat <- as.data.frame(matrix(rnorm(100)+ 0.000000000000012, ncol = 10))
# not that reading/writing has anything to do with this, but just to
# prove it
write.table(dat, file = "~/tmp/temp.csv", sep = ",")
dat <- read.table("~/tmp/temp.csv", sep = ",", header = TRUE)
dat
options(digits = 14)
dat

or

print(dat, digits = 14)

G

Ps. Wasn't sure about the etiquette of replying to R-bugs in recipients,
so deleted it in case this caused further work for the maintainer(s) of
the bug repository. Sorry if this isn't desirable.

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Gavin Simpson
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