rain

https://www.youtube.com/watch?v=w4mc2xnIKBY

This follows a basic game loop.

1. Display
2. Get Input (only time marching on, as this is a simulation not an interactive game)
3. Update Data based on Input
4. goto 1.

We have a list of rows; each of which has a list of columns (like a spreadsheet or graph paper or battle ship).

We display the integer values as one of eight letters " .,:;|oO" (space through capital O).

We cycle through all the rows and columns. For each we might add a drop of water by adding 1 to the existing value.

If there are enough drops in one position we move some or all of the drops to the position below (row index + 1).

The core of all this is the update() function. Here it is with some comments:

def update():

#LOOP THROUGH ALL ROWS

for ir in range(len(data)-1,-1,-1):

#LOOP THROUGH ALL COLUMNS

for ic, c in enumerate(data[ir]):

  #ONCE IN A THOUSAND CHANCE WE WILL 
  
  if randint(1,1000) > 999:
  
    #ADD A SINGLE RAINDROP TO THIS ROW/COLUMN POSITION
    
    data[ir][ic] += randint(1,3)
    
  #IF THERE AT LEAST 2 RAINDROPS IN THIS POSITION
  
  if c > 2:
  
    #REMOVE THE RAIN FROM THIS POSITION
    
    data[ir][ic] -= c
    
    #IF NOT ON THE BOTTOM ROW
    
    if ir < len(data) -1:
    
      #ADD THE SUBTRACTED AMOUNT OF RAIN TO THE ROW BELOW
      
      data[ir+1][ic] += c