Full_Name: Dr. Alex Sheppard Version: 2.7.1 OS: Linux Debian Lenny Submission from: (NULL) (79.73.224.62) After scanning from an open (text) connection, then seeking, then scanning again, the second scan returns incorrect result. It looks like the first byte scanned was from the pre-seek file position, then it continues to read from the post-seek file position. To reproduce: #Put 3x3 matrix in a file
write.matrix(t(matrix(1:9,nrow=3)),file="TEST.txt",sep="\t")
#Open file as text
fd <- file("TEST.txt",open="rt")
#scan a couple of fields - this looks fine so far
scan(file=fd,what=double(),n=2)
Read 2 items [1] 1 2 #seek back to start of file
seek(con=fd,where=0,origin="start")
[1] 5 #scan fields again - this doesn't work properly
scan(file=fd,what=double(),n=2)
Read 2 items
[1] 31 2
This happens when either n or nmax arguments are used to control number of
fields read. Problem does not occur when using nlines argument instead. The seek
appears to work ok, as doing readChar(fd,n=1) after the seek operation correctly
returns "1".
Also, if the file is opened as binary, i.e. fd=file("TEST.txt",open="rb") , all
works fine.