Convert a string of integers represented in different formats into a list of integers Python

Question

Is there an easy way, apart from looping, to convert this kind of representation to a list of integers?

s = ['0','1','2:5','0x4']

to

list_i=[0,1,2,3,4,5,0,0,0,0]

Answer 1

You can use a list comprehension with the ternary operator like this:

list_i = [i for t in s for i in ((lambda r: range(int(r[0]), int(r[1]) + 1))(t.split(':')) if ':' in t else (lambda r: [int(r[0])] * int(r[1]))(t.split('x')) if 'x' in t else (int(t),))]

or you can use a for loop instead:

list_i = []
for token in s:
    if ':' in token:
        start, end = token.split(':')
        list_i.extend(list(range(int(start), int(end) + 1)))
    elif 'x' in token:
        number, repeat = token.split('x')
        list_i.extend([int(number)] * int(repeat))
    else:
        list_i.append(int(token))

Answer 2

No, there isn't. You need to handle the special strings seperately. You need to loop through the list, check if the given element is a simple integer, if so, convert it as it is. If the element being considered is special ( 0x4 or 2:5 in your case), you need code to handle it. Try this:

oldList = ['0','1','2:5','0x4'] 

def isInt(val):
    try:
        int(val)
        return True
    except ValueError:
        return False

def convertRange(val):
    l = val.split(':')
    return [x for x in range(int(l[0]), int(l[1])+1)]


def convertRepetition(val):
    l = val.split('x')
    return [int(l[0]) for i in range(0, int(l[1]))]

newList = []

for elem in oldList:
    if ':' in elem:
        newList.extend(convertRange(elem))

    elif 'x' in elem:
        newList.extend(convertRepetition(elem))

    elif isInt(elem):
        newList.append(int(elem))

print(newList)

the convertRange() and convertRepitition() functions take care of the two special cases your question mentions.

Answer 3

If you have the freedom to redefine how the s-list is set, you can use python syntax like this

s = ['[0]','[1]','range(2,6)','[0]*4'] 
list_i = []
[exec('list_i+='+i) for i in s]
print(list_i)
# which outputs
[0, 1, 2, 3, 4, 5, 0, 0, 0, 0]