Using field calculator to auto-increment within a range?

Question

I am trying to use field calculator to number points between -700 and 700. I have used this code block:

rec=0 
def autoIncrement(): 
 global rec 
 pStart = 700
 pInterval = -1 
 if (rec == 0): 
 rec = pStart 
 else: 
 rec += pInterval 
return rec

which works great, but only numbers between 700 and 0, but I would like it to number all the way to -700 before starting over. Is this possible with this approach or do I need to try a different method?

• FelixIP: Try divmod or % operator on autoincremented value and 1400-result
• miss_lilly_belle: Sorry, I'm new to this - I'm not sure I understand what you mean by this, could you explain further?

Answer 1

Assuming you have 1401 points to number and you are trying to autodecrement, try the code below:

rec=-700 
def autoIncrement(): 
 global rec 
 pStart = 700 
 pInterval = 1 
 if (rec == -700): 
 rec = pStart 
 else: 
 rec -= pInterval 
 return rec

I should say though, this is an easy fix, not a proper solution to your problem or possible derivatives!

• miss_lilly_belle: This did what I needed and was more 'proper' than the clunky temporary solution I came up with. Thanks!