[Rd] boundary case anomaly

Robert Gentleman rgentlem at fhcrc.org
Sun Apr 8 10:09:05 CEST 2007

  Any reason these should be different?

  x=matrix(0, nr=0, nc=3)
  colnames(x) = letters[1:3]
#[1] a b c
#<0 rows> (or 0-length row.names)
  y=vector("list", length=3)
  names(y) = letters[1:3]
#NULL data frame with 0 rows

both should have names (the second one does not) and why print something 
different for y?

  The two of the last three examples refer to a "NULL data frame", eg
   (d00 <- d0[FALSE,])  # NULL data frame with 0 rows

  but there is no description of what a NULL data frame should be (zero 
rows or zero columns, or either or both - and why a special name?)

  best wishes

Robert Gentleman, PhD
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M2-B876
PO Box 19024
Seattle, Washington 98109-1024
rgentlem at fhcrc.org

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