python simplify svg for webgl demo problem

simplify_svg.py

from traceback import print_exc
import sys

def simplify_svg(svg_str,to_integer=True):
    
    def to_number(s):
        try:
            if to_integer:
                return int(float(str(s).strip()))
            else:
                return float(str(s).strip())
        except:
            print(('number parsing error',s),file=sys.stderr)

    
    # python2-3 workaround
    try: from itertools import izip
    except: izip = zip

    def pairwise(iterable):
        a = iter(iterable)
        return izip(a, a)

            
    def parse_coord(coord_str):
        _x, _y = pairwise(re.split(r', ',coord_str))
        return to_number(_x),to_number(_y)
        
        
    def parse_coord_list(coord_list_str):
        return [(to_number(_x),to_number(_y)) for _x, _y in pairwise(re.split(r', ',coord_list_str))]


    svg_seq = re.split(r'([mcz])',svg_str)[1:]
    
    start_coord = (0.0, 0.0)
    last_coord  = (0.0, 0.0)
    
    simplified_seq = []

    i = 0
    while i < len(svg_seq):
        code = svg_seq[i]
        
        print(('trace','i',i,'code',code))
        
        lx, ly = last_coord
        
        if code in 'MLCSQT': # <code> x1 y1 x2 y2 ...
            param = svg_seq[i+1]
            for x, y in parse_coord_list(param):
                simplified_seq.append('{}{},{}'.format(code,x,y))
                lx, ly = x, y
            last_coord = lx, ly
            if code == 'M':
                start_coord = last_coord
            i += 2
            continue
        
        if code in 'mlcsqt': # <code> dx1 dy1 dx2 dy2 ...
            param = svg_seq[i+1]
            for dx, dy in parse_coord_list(param):
                simplified_seq.append('{}{},{}'.format(code,dx,dy))
                lx, ly = last_coord[0] + dx, last_coord[1] + dy
            last_coord = lx, ly
            if code == 'm':
                start_coord = last_coord
            i += 2
            continue
        
        if code in 'H': # <code> x1 x2 ...
            param = svg_seq[i+1]
            for x in [to_number(s) for s in re.split(r', ',param)]:
                simplified_seq.append('{}{}'.format(code,n))
                lx, ly = x, last_coord[1]
            last_coord = lx, ly
            i += 2
            continue
        
        if code in 'V': # <code> y1 y2 ...
            param = svg_seq[i+1]
            for y in [to_number(s) for s in re.split(r', ',param)]:
                simplified_seq.append('{}{}'.format(code,n))
                lx, ly = last_coord[0], y
            last_coord = lx, ly
            i += 2
            continue
        
        if code in 'h': # <code> dx1 dx2 ...
            param = svg_seq[i+1]
            for dx in [to_number(s) for s in re.split(r', ',param)]:
                simplified_seq.append('{}{}'.format(code,n))
                lx, ly = last_coord[0] + dx, last_coord[1]
            last_coord = lx, ly
            i += 2
            continue
        
        if code in 'v': # <code> dy1 dy2 ...
            param = svg_seq[i+1]
            for dy in [to_number(s) for s in re.split(r', ',param)]:
                simplified_seq.append('{}{}'.format(code,n))
                lx, ly = last_coord[0], last_coord[1] + dy
            last_coord = lx, ly
            i += 2
            continue
        
        if code in 'Zz': # Z or z
            simplified_seq.append('{}'.format(code))
            last_coord = start_coord
            i += 1
            continue

#         if code == 'A': # A rx ry a f1 f2 x y
#             pass
        
#         if code == 'a': # a rx ry a f1 f2 dx dy
#             pass

        raise RuntimeError(('unknown code',code))
    
    return ' '.join(simplified_seq)