String to int newbie question

[Anton Vredegoor]

Luka Milkovic <Luka.Milkovic at public_MAKNIME_.srce.hr> wrote:

>Ok, I proabably haven't been clear enough. Here is what I really want to
>do: I have a list of strings ( the content of strings are actually
>numbers ), for example I have the following list: ['4312', '7599',
>'0724', '0003']. The things I need to do is to change the strings inside
>the list to integers and then write the list to a file ( I know how to do

Well, you didn't specify which integers correspond to which strings
:-)

>the latter:). The problem is, if I change it with
>int(my_string_inside_the_list) I won't get the same numbers, and I need
>to have the content of the string and integer the same. So, after the
>conversion of that list, what I want to have is: [4312, 7599, 0724, 0003]
>and NOT [4312, 7599, 724, 3].

If you don't mind the strings corresponding to unusual integers
there's another way to do it.

Anton.

class sequencer:
    
    def __init__(self,items):
        #initialize an instance with the list of possible items
        self.items = items
        self.base = len(items)

    def __getitem__(self,n):
        # return the list of items with rank n
        result,todo = [], n
        while todo >= 0:
            todo,i = self.splitat(0,todo)    
            result.append(self.items[i])
        result.reverse()
        return result

    def rank(self,L):
        #compute the rank of a list of items
        r = self.items.index(L[0])
        for x in L[1:]:
            i = self.items.index(x)
            r = self.concat(r,i)
        return r

    def concat(self,a,b):
        # compute the number for  a + b concatenated
        i,j = 0,1
        while i <= b:
            j = j * self.base
            i = i + j
        return j*(a+1)+b
    
    def splitat(self,pos,x):
        #compute the numbers for x splitted at position pos
        i,j = 0,1  
        for k in range(pos+1):
            j = j * self.base
            i = i + j
        a = (x-i)/j
        b = x-j*(a+1)
        return a,b

def test():
    seq = sequencer('0123456789')
    ss = ['4312','7599','0724','0003']
    ints,sstest = [],[]
    for s in ss:
        ints.append(seq.rank(s))
    print ints
    for i in ints:
        sstest.append(''.join(seq[i]))
    print sstest
    assert ss == sstest

if __name__=='__main__':
    test()