A bit late for Santa, but on my wish-list nevertheless: is there any chance that "scan" and "readLines" could be extended to take a parameter "until" or "EOF.marker", which would be a character string that (if encountered while reading) would cause the reading to stop, just as if an end-of-file had been found? [But leaving a connection open, so that subsequent calls could read the rest of the file.] Compatibility could be ensured by making "until" default to as.character( NA), which can never be encountered. If the "until" string isn't encountered when reading, then reading continues until a real end-of-file (or the "n" parameter is satisfied). This would be useful in all sorts of contexts; one example is in processing a single data file that's made up of multiple segments each of different formats. cheers Mark ******************************* Mark Bravington CSIRO (CMIS) PO Box 1538 Castray Esplanade Hobart TAS 7001 phone (61) 3 6232 5118 fax (61) 3 6232 5012 Mark.Bravington at csiro.au
Wish list: add an "until" or "EOF.marker" parameter to scan & rea dLines
2 messages · Mark Bravington, Brian Ripley
Why is this necessary? There are plenty of ways to do this already via connections, e.g copy line-by-line to an anonymous file connection and then scan from that. Yes, it is useful, and that's why people already supplied you with a more general tool, namely connections. Please do look at the internals of scan before suggesting complicating it further: it is already close to unmaintainable. I don't think R-help is the place for wishlist items: there is R-devel and the R-bugs list has a wishlist section too (but please note that this gets little action due to the perceived usefulness of the wishes).
On Fri, 27 Dec 2002 Mark.Bravington at csiro.au wrote:
A bit late for Santa, but on my wish-list nevertheless: is there any chance that "scan" and "readLines" could be extended to take a parameter "until" or "EOF.marker", which would be a character string that (if encountered while reading) would cause the reading to stop, just as if an end-of-file had been found? [But leaving a connection open, so that subsequent calls could read the rest of the file.] Compatibility could be ensured by making "until" default to as.character( NA), which can never be encountered. If the "until" string isn't encountered when reading, then reading continues until a real end-of-file (or the "n" parameter is satisfied). This would be useful in all sorts of contexts; one example is in processing a single data file that's made up of multiple segments each of different formats. cheers Mark ******************************* Mark Bravington CSIRO (CMIS) PO Box 1538 Castray Esplanade Hobart TAS 7001 phone (61) 3 6232 5118 fax (61) 3 6232 5012 Mark.Bravington at csiro.au
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Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595