main.py

from xml.dom import minidom

root = minidom.parse("weave.svg")

joinCount = 0

lines = []
for l1 in root.getElementsByTagName("line"):
    x1 = l1.attributes['x1'].value
    y1 = l1.attributes['y1'].value
    x2 = l1.attributes['x2'].value
    y2 = l1.attributes['y2'].value
    lines.append((x1, y1, x2, y2))

print(len(lines))
output = []
while len(lines):
    # Start a random line
    x1, y1, x2, y2 = lines.pop()

    # Then try to grow it in both directions,
    # until no other line fits on either end.
    # Possible improvment: Check if reversing the target line makes it fit
    found = True
    while found:
        found = False
        for l2 in lines:
            x1_, y1_, x2_, y2_ = l2
            # It seems like the for loop doesn't mind
            # if we delete from the list it's working on
            if found:
                break
            if x2 == x1_ and y2 == y1_:
                x2 = x2_
                y2 = y2_
                found = True
            elif x1 == x2_ and y1 == y2_:
                x1 = x1_
                y1 = y1_
                found = True
            if found:
                lines.remove(l2)
                joinCount += 1

    output.append((x1, y1, x2, y2))

print(len(output))
cn1 = root.childNodes[1]
for child in cn1.childNodes:
    cn1.removeChild(child)

for line in output:
    newline = root.createElement("line")
    newline.setAttribute("class", "st0")
    newline.setAttribute("x1", line[0])
    newline.setAttribute("y1", line[1])
    newline.setAttribute("x2", line[2])
    newline.setAttribute("y2", line[3])
    cn1.appendChild(newline)

print("Joined " + str(joinCount) + " lines.")

file = open("output.svg", 'w')
file.write(root.toxml())