# -*- coding: utf-8 -*-
"""
Created on Fri Apr 26 11:30:51 2013

@author: svenni
"""

from pylab import *
from scipy.ndimage import measurements

def walk(z):
    #
    # Left turning walker
    #
    # Returns left: nr of times walker passes a site
    #
    # First, ensure that array only has one contact point at left and
    # right : topmost points chosen
    #
    nx = z.shape[0]
    ny = z.shape[1]
    i = where(z > 0)
    ix0 = 0 # starting row for walker is always 0
    iy0 = i[1][where(i[0] == 0)][0] # starting row (first element where there is a matching column which is zero)
    print "Starting walk in x=" + str(ix0) + " y=" + str(iy0)
    # First do left-turning walker
    directions = zeros((4,2), int)
    directions [0,0] = -1 # west
    directions [0,1] = 0
    directions [1,0] = 0 # south
    directions [1,1] = -1
    directions [2,0] = 1 # east
    directions [2,1] = 0
    directions [3,0] = 0 # north
    directions [3,1] = 1
    nwalk = 1
    ix = ix0
    iy = iy0
    direction = 0 # 0 = west, 1 = south, 2 = east, 3 = north
    left = zeros((nx,ny),int)
    right = zeros((nx,ny),int)
    while (nwalk >0):
        left[ix,iy] = left[ix,iy] + 1
        # Turn left until you find an occupied site
        nfound = 0
        while (nfound==0):
            direction = direction - 1
            if (direction < 0):
                direction = direction + 4
            
            # Check this direction
            iix = ix + directions[direction,0]
            iiy = iy + directions[direction,1]
            if (iix >= nx):
                nwalk = 0 # Walker escaped
                nfound = 1
                iix = nx
                ix1 = ix
                iy1 = iy
                    
            # Is there a site here?
            elif(iix >= 0):
                if(iiy >= 0):
                    if (iiy < ny):
                        if (z[iix,iiy]>0): # there is a site here, move here
                            ix = iix
                            iy = iiy
                            nfound = 1
                            direction = direction + 2    
                            if (direction > 3):
                                direction = direction - 4
        
    
    #left
    nwalk = 1
    ix = ix0
    iy = iy0
    direction = 1 # 1=left, 2 = down, 3 = right, 4 = up
    while(nwalk >0):
        right[ix,iy] = right[ix,iy] + 1
        # ix,iy
        # Turn right until you find an occupied site
        nfound = 0
        while (nfound==0):
            direction = direction + 1
            if (direction > 3):
                direction = direction - 4
            
            # Check this directionection
            iix = ix + directions[direction,0]
            iiy = iy + directions[direction,1]
            if (iix >= nx):
                if (iy >= iy1):
                    nwalk = 0 # Walker escaped
                    nfound = 1
                    iix = nx
                    
            # Is there a site here?
            elif(iix >= 0):
                if(iiy >= 0):
                    if (iiy < ny):
                        if (iix < nx):
                            if (z[iix,iiy]>0): # there is a site here, move here
                                ix = iix
                                iy = iiy
                                nfound = 1
                                direction = direction - 2
                                if (direction <0):
                                    direction = direction + 4
                                    
    return left, right