drawline.py

l = [[" "]]
l_len_y = len(l)
l_len_x = len(l[0])

class point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

def out():
    for i in l:
        print("".join(i))

def plot(p, c):
    x = p.x; y = p.y
    global l_len_y
    if y > l_len_y:
        for i in range(l_len_y, y):
            l.append([" " for n in range(l_len_x)])
        l_len_y = y
    global l_len_x
    if x > l_len_x:
        for i in range(l_len_y):
            l[i].extend([" " for n in range(x-l_len_x)])
        l_len_x = x
    l[y-1][x-1] = c

def draw_line(p0, p1, c):
    x0 = p0.x; y0 = p0.y
    x1 = p1.x; y1 = p1.y
    del p0, p1
    if x0 < 0 or x1 < 0 or y0 < 0 or y1 < 0:
        print("negative coordinate")
        return
    if x1 == x0:
        for y in range(y0, y1):
            plot(point(x0, y), c)
        return
    s = (y1-y0)/(x1-x0)
    if s < -1 or s > 1:
        if y0 > y1:
            x0, x1 = x1, x0
            y0, y1 = y1, y0
        s = 1/s
        for y in range(y0, y1+1):
            x = x0+round(s*(y-y0))
            plot(point(x, y), c)
    else:
        if x0 > x1:
            x0, x1 = x1, x0
            y0, y1 = y1, y0
        for x in range(x0, x1+1):
            y = y0+round(s*(x-x0))
            plot(point(x, y), c)

a = "."
p = "*"
p0 = point(3, 1);  p1 = point(22, 10); p2 = point(41, 1)
p3 = point(1, 15); p4 = point(43, 15); p5 = point(22, 15)
draw_line(p0, p1, a)
draw_line(p1, p2, a)
draw_line(p0, p3, a)
draw_line(p2, p4, a)
draw_line(p3, p4, a)
draw_line(p1, p5, a)
plot(p0, p)
plot(p1, p)
plot(p2, p)
plot(p3, p)
plot(p4, p)
plot(p5, p)
out()

import os
if 'win' in os.sys.platform:
    os.system("PAUSE")