How to read number count of words? - tcl

Question

How to read number count of words?
Lines has this format:
vertices_count
X, Y
X, Y
X, Y
(X, Y pair can be in the same line)
for example:
3
12.5, 56.8
12.5, 56.8
12.5, 56.8
I would like to read vertices_count number of words(escaping comma):
So for above example reading words should be:
12.5 56.8 12.5 56.8 12.5 56.8

Answer 1

set fh [open f r]
gets $fh num
read $fh data
close $fh
set number_re {-?\d+(?:\.\d*)?|-?\d*\.\d+}
set vertices {}
foreach {_ x y} [regexp -inline -all "($number_re),\\s*($number_re)" $data] {
lappend vertices $x $y
if {[llength $vertices] == $num * 2} break
}
puts $vertices
# => 12.5 56.8 12.5 56.8 12.5 56.8
while {[llength $vertices] < $num * 2} {
gets $fh line
foreach {_ x y} [regexp -inline -all "($number_re),\\s*($number_re)" $line] {
lappend vertices $x $y
if {[llength $vertices] == $num * 2} break
}
}
close $fh

Answer 2

I'm still not clear exactly what you are after. Here is some code to read data from a named file. Judging from your other question, you can have several sets of data in your input stream and this code returns them all as a list. Each element of the list is one set of coordinates
# Read the input from file
set fil [open filename.file]
set input [read $fil]
close $fil
set data [list]; # No output so for
set seekCount yes; # Next token is a vertex count
foreach token [string map {, " "} $input] {
# Convert commas to spaces
if {$seekCount} {
set nCoords [expr $token * 2];
# Save number of coordinates
set datum [list]; # Clean out vertex buffer
} else {
lappend datum $token; # Save coordinate
incr nCoords -1
if {$nCoords <= 0} {
# That was the last coordinate
lappend data $datum; # Append the list of coordinates
set seekCount yes; # and look for anopther count
}
}
}
This is a very quick-and-dirty solution, which makes no attempt to handle errors. One thing, however that it will cope with is variable amounds of whitespace and missing whitespace after the commas.
Good luck, I hope this helps.

Answer 3

This procedure first reads a count line, then reads that number of lines and puts as a list into $varName. It returns the number of elements in $varName, or -1 if EOF occured before a count was read.
proc getNLines {stream varName} {
upvar 1 $varName lines
set lines {}
if {[gets $stream n] < 0} {
return -1
}
while {$n > 0} {
if {[gets $stream line] < 0} {
error "bad data format"
}
lappend lines $line
incr n -1
}
return [llength $lines]
}
while {[getNLines stdin lines] >= 0} {
# ...
}