Solution P4.6.2
The method listed below can be called on a Polymer object to save an SVG representation of the polymer. It centres the image on a $500 \times 500$ pixel canvas and projects the monomer unit positions onto the $(x,y)$ plane.
:::python
def save_svg(self, svg_name='polymer.svg'):
canvas_width = 500; canvas_height = 500
fo = open(svg_name, 'w')
print("""<?xml version="1.0" encoding="utf-8"?>
<svg xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink"
width="{}" height="{}" style="background: {}">""".format(
canvas_width, canvas_height, '#ffffff'), file=fo)
ccx, ccy = canvas_width / 2, canvas_height / 2
scale = 10
x, y, z = zip(*self.xyz)
xmin, xmax, ymin, ymax = min(x), max(x), min(y), max(y)
dmax = max(xmax-xmin, ymax-ymin)
scale = min(canvas_width, canvas_height) / dmax
for i in range(1, self.N):
x1, y1 = x[i-1]*scale + ccx, y[i-1]*scale + ccy
x2, y2 = x[i]*scale + ccx, y[i]*scale + ccy
print('<line x1="{:.1f}" y1="{:.1f}" x2="{:.1f}" y2="{:.1f}"'
' style="stroke: {:s}; stroke-width: {:d};"/>'.format(
x1, y1, x2, y2, 'black', 2), file=fo)
print('</svg>', file=fo)
An example output image is given below.
