Math::PlanePath::File -- points from a file

       This path reads X,Y points from a file to present in PlanePath style.  It's slightly preliminary yet but
       is handy to get numbers from elsewhere into a PlanePath program.

       The intention is to be flexible about the file format and to auto-detect as far as possible.  Currently
       the only format is plain text, with an X,Y pair, or N,X,Y triplet on each line

           5,6                   # X,Y
           123  5 6              # N,X,Y

       Numbers can be separated by a comma or just spaces and tabs.  Lines not starting with a number are
       ignored as comments (or blanks).  N values must be integers, but the X,Y values can be fractions like 1.5
       too, including exponential floating point 1500.5e-1 etc.

       See "FUNCTIONS" in Math::PlanePath for behaviour common to all path classes.

       "$path = Math::PlanePath::File->new (filename => "/my/file/name.txt")"
           Create and return a new path object.

       "($x,$y) = $path->n_to_xy ($n)"
           Return the X,Y coordinates of point number $n on the path.

       "$n = $path->xy_to_n ($x,$y)"
           Return the point number for coordinates "$x,$y".

           In  the  current  code  an "$x,$y" within a unit circle or square of a point from the file gives that
           point.  But perhaps in the future some attention could be paid to apparent spacing of  points  closer
           than that.

       "$bool = $path->x_negative()"
       "$bool = $path->y_negative()"
           Return true if there are any negative X or negative Y coordinates in the file.

       "$n = $path->n_start()"
           Return  the  first N in the path.  For files of just X,Y points the start is N=1, for N,X,Y data it's
           the first N.

       "$str = $path->figure()"
           Return a string name of the figure (shape) intended to be drawn at each $n position.  In the  current
           code  if  all X,Y are integers then this is "square", otherwise it's "circle".  But perhaps that will
           change.

       <http://user42.tuxfamily.org/math-planepath/index.html>

       Copyright 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Kevin Ryde

       This file is part of Math-PlanePath.

       Math-PlanePath is free software; you can redistribute it and/or modify it under  the  terms  of  the  GNU
       General  Public  License  as  published  by  the  Free Software Foundation; either version 3, or (at your
       option) any later version.

       Math-PlanePath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without  even
       the  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
       License for more details.

       You should have received a copy of the GNU General Public License along with Math-PlanePath.  If not, see
       <http://www.gnu.org/licenses/>.

perl v5.32.0                                       2021-01-23                         Math::PlanePath::File(3pm)

       Math::PlanePath::File -- points from a file

       Math::PlanePath

        use Math::PlanePath::File;
        my $path = Math::PlanePath::File->new (filename => 'foo.txt');
        my ($x, $y) = $path->n_to_xy (123);