Funny behaviour of my recursive function

Question

t = 8
string = "1 2 3 4 3 3 2 1"
string.replace(" ","")
string2 = [x for x in string]
print string2

for n in range(t-1):
    string2.remove(' ')

print string2

def remover(ca):
    newca = []
    print len(ca)

    if len(ca) == 1:
        return ca
    else:
        for i in ca:
            newca.append(int(i) - int(min(ca)))

    for x in newca:
        if x == 0:
            newca.remove(0)

    print newca
    return remover(newca)

print (remover(string2))

It's supposed to be a program that takes in a list of numbers, and for every number in the list it subtracts from it, the min(list). It works fine for the first few iterations but not towards the end. I've added print statements here and there to help out.

EDIT:

t = 8

string = "1 2 3 4 3 3 2 1"

string = string.replace(" ","")

string2 = [x for x in string]

print len(string2)

def remover(ca):

    newca = []

    if len(ca) == 1: return()

    else:
        for i in ca:
            newca.append(int(i) - int(min(ca)))

    while 0 in newca:
        newca.remove(0)

    print len(newca)

    return remover(newca)


print (remover(string2))

Answer 1

for x in newca:
    if x == 0:
        newca.remove(0)

Iterating over a list and removing things from it at the same time can lead to strange and unexpected behvaior. Try using a while loop instead.

while 0 in newca:
    newca.remove(0)

Or a list comprehension:

newca = [item for item in newca if item != 0]

Or create yet another temporary list:

newnewca = []
for x in newca:
    if x != 0:
        newnewca.append(x)

print newnewca

return remover(newnewca)

Answer 2

(Not a real answer, JFYI:)

Your program can be waaay shorter if you decompose it into proper parts.

def aboveMin(items):
  min_value = min(items) # only calculate it once
  return differenceWith(min_value, items)

def differenceWith(min_value, items):
  result = []
  for value in items:
    result.append(value - min_value)
  return result

The above pattern can, as usual, be replaced with a comprehension:

def differenceWith(min_value, items):
  return [value - min_value for value in items]

Try it:

>>> print aboveMin([1, 2, 3, 4, 5])
[0, 1, 2, 3, 4]

Note how no item is ever removed, and that data are generally not mutated at all. This approach helps reason about programs a lot; try it.

Answer 3

So IF I've understood the description of what you expect,

I believe the script below would result in something closer to your goal.

Logic:

• split will return an array composed of each "number" provided to raw_input, while even if you used the output of replace, you'd end up with a very long number (you took out the spaces that separated each number from one another), and your actual split of string splits it in single digits number, which does not match your described intent
• you should test that each input provided is an integer
• as you already do a print in your function, no need for it to return anything
• avoid adding zeros to your new array, just test first

---

string = raw_input()

array = string.split()
intarray = []
for x in array:
  try:
    intarray.append(int(x))
  except:
    pass

def remover(arrayofint):
  newarray = []
  minimum = min(arrayofint)
  for i in array:
    if  i > minimum:
      newarray.append(i - minimum)
  if len(newarray) > 0:
    print newarray
    remover(newarray)

remover(intarray)