CODEWITHSUNDEEP
pythonlistnumpy
Bob
Bob

Reputation: 10795

python loop over continuously expanding list

I have a list containing values (tuples in my case) - in the beginning there is 1 element. I need to loop over a list and for the last value in the list apply some computations, which will provide me with the next list element. After that I need to concatenate those lists and using the last value of the list compute next element. And so on...

How can it be done? NumPy also can be used.

Now I do like this, but it does not work

while True:
    lst = [1]
    print(lst)
    for i in range(len(lst)):
        elem = lst[-1]
        new = elem + 10 // dummy computations
        lst.append(new)

Upvotes: 2

Views: 4225

Answers (2)

askewchan
askewchan

Reputation: 46530

If you just want to loop through the list later, you can build a generator:

def f(elem):
    return elem + 10

def lst(init):
    yield init
    while True:
        next = f(init)
        yield next
        init = next

This goes on forever, so be sure your loop has some break in it:

for i in lst(1):
    print i
    if i > 100:
        break

prints:

1
11
21
31
41
51
61
71
81
91
101

Upvotes: 3

shx2
shx2

Reputation: 64308

How is this for a start?

def f(x):
    return 2*x+1

a = [ 1 ]
while len(a) < 8:
   x = a[-1]
   y = f(x)
   a.append(y)

a
=> [1, 3, 7, 15, 31, 63, 127, 255]

Upvotes: 2

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