ARTICLE AD BOX
Your code does not work because when you iterate over the dictionary's values, the value is being copied into a new variable value. You can update this, but it will not update the original value in the dictionary. Also, a better way to test to see if a variable is an int is to use isinstance since this will also work for subclasses of int:
d = all_variables['Input Parameter'] for key, value in d.items(): # is it a negative int or float? if isinstance(value, (int, float)) and value < 0: d[key] = -value