What to use for end x,y corodinates in addLine using a list

Question

i need to draw a line between several cities using add line. The cities coordinates are taken from a list. However, i dont know how i should input the end coordinates. Heres the code so far:

def a2level1():
  cityXCoordinate=[ 43, 93,180,205,254,310,326,348,372,398]
  cityYCoordinate=[308,145, 82,199,335,373,432,346,333,263]

  map = makePicture()
  show(map)
  cities =  [requestInteger("Enter the number of cities you would like to visit")]
  for number in cities:
    print number
    for number in range(0,number):
      print number
      city = [requestInteger("Please choose a city number")]
      while city <= number:
          city = [requestInteger("Please choose a city number")]
          addLine(map,cityXCoordinate[city],cityYCoordinate[city], cityXCoordinate[city], cityYCoordinate[city])


  repaint(map)

Answer 1

I am naming the x and y coordinates for the two cities separately and making them smaller for readability:

#addLine(map,cityXCoordinate[city],cityYCoordinate[city],
#cityXCoordinate[city], cityYCoordinate[city])

cityXCoordinate1= x1
cityYCoordinate1 = y1
cityXCoordinate2 = x2
cityYCoordinate2 = y2

In this case I am not repainting the image, but creating a second image, so the first is not overwritten, that's your choice.

#Find the max height and width of your map
w= getWidth (map)
h = getHeight(map)
newPic = makeEmptyPicture(w,h)

#loop through the coordinates of the map
for y in range (0,h):
  for x in range (0, w):

  #select the points forming a straight line between the two points
  if (x==((y-y1)*(x2-x1)/(y2-y1)+x1)):
    newPxl= getPixel(newPic,x,y)
    #color those pixels black
    color = makeColor(0,0,0)
    setColor (newPxl, color)
  else:
    #color the remaining map as it is
    pxl = getPixel(pic, x, y)
    newPxl= getPixel(newPic,x,y)
    color = getColor(pxl)
    setColor (newPxl, color)