long story short. Can someone explain it to me how is it that be, simple line of code can do the same as all of the for loop written by me?

def z1(code1, code2):
   parse = lambda x: int(x.replace('-', ''))
   code1, code2 = parse(code1), parse(code2)
   print(code1, code2)
   return ["d-d" % divmod(x, 1000) for x in range(code1, code2 1)] <---

here's my solution:

def z2(code1, code2):
  codes = []
  parse = lambda x: int(x.replace('-', ''))
  code1, code2= parse(code1), parse(code2)
  for x in range(code1, code2 1):
      x = str(x)
      a = x[0:2]
      b = x[2:6]
      c = a "-" b
      codes.append(f"{c}")
  return codes

CodePudding user response：

["d-d" % divmod(x, 1000) for x in range(code1, code2 1)]

This is called list comprehension, allow writing more concise code than creating empty list and then append-ing in loop. Consider following example

squares = []
for i in range(5):
    squares.append(i**2)

is equivalent to

squares = [i**2 for i in range(5)]