python 3.x - Simple square grid lookup

Question

I'm drawing a blank on trying to come up with a simple square grid lookup in python and hope someone can give me some pointers here. Let's say I have a 5x5 grid, starting from the center (3,3), I'd like the lookup to step up the radius outputting the peripheral coordinates like this:

 Radius     Output   
   0        [[3,3]]   
   1        [[2,2], [2,3], [2,4], [3,2], [3,4], [4,2], [4,3], [4,4]]   
   2        [[1,1], [1,2], [1,3], [1,4], [1,5], [2,1], [2,5], [3,1], 
             [3,5], [4,1], [4,5], [1,1], [1,2], [1,3], [1,4], [1,5]]

Any pointers will be greatly appreciated!

UPDATE: The code I have at the moment is:

center_coordinate = [3, 3]
completed_locations = [center_coordinate]
radius = 0
max_radius = 3
while radius != max_radius:
    x_grid = [x for x in range(center_coordinate[0] - radius, center_coordinate[0] + radius + 1)]
    y_grid = [y for y in range(center_coordinate[0] - radius, center_coordinate[0] + radius + 1)]
    locations = []
    for x in x_grid:
        for y in y_grid:
            if [x, y] not in completed_locations:
                locations.append([x, y])
                completed_locations.append([x, y])
    radius += 1
    print(radius, locations)

While this does do the job, I am looking for a solution that wouldn't require me to cross check each location as it iterates through.. the actual grid size i'll be working against is 750x750 and this particular module will be called on regularly.

question from:https://stackoverflow.com/questions/65858565/simple-square-grid-lookup

Answer 1

For such kind of problem where you traverse through grids to form circle then Midpoint circle algorithm is a possibility

For example to demonstrate you can use something like this according to your need to implement your requirement

def midPointCircleDraw(x_centre, y_centre, r): 
    x = r 
    y = 0
    
    print("(", x + x_centre, ", ",  
               y + y_centre, ")",  
               sep = "", end = "")  
    
    
    if (r > 0) : 
      
        print("(", x + x_centre, ", ", 
                  -y + y_centre, ")",  
                  sep = "", end = "")  
        print("(", y + x_centre, ", ",  
                   x + y_centre, ")", 
                   sep = "", end = "")  
        print("(", -y + x_centre, ", ",  
                    x + y_centre, ")", sep = "")  
      
     
    P = 1 - r  
  
    while x > y: 
      
        y += 1
          
       
        if P <= 0:  
            P = P + 2 * y + 1
              
         
        else:          
            x -= 1
            P = P + 2 * y - 2 * x + 1
          
        if (x < y): 
            break
           
        print("(", x + x_centre, ", ", y + y_centre, 
                            ")", sep = "", end = "")  
        print("(", -x + x_centre, ", ", y + y_centre,  
                             ")", sep = "", end = "")  
        print("(", x + x_centre, ", ", -y + y_centre, 
                             ")", sep = "", end = "")  
        print("(", -x + x_centre, ", ", -y + y_centre, 
                                        ")", sep = "")  
          
         
        if x != y: 
          
            print("(", y + x_centre, ", ", x + y_centre,  
                                ")", sep = "", end = "")  
            print("(", -y + x_centre, ", ", x + y_centre, 
                                 ")", sep = "", end = "")  
            print("(", y + x_centre, ", ", -x + y_centre, 
                                 ")", sep = "", end = "")  
            print("(", -y + x_centre, ", ", -x + y_centre,  
                                            ")", sep = "")