Hold An Object, Using Class In Python

I write a program to weave lists of floats together, for example: l1 = [5.4, 4.5, 8.7] l2 = [6.5, 7.8] l3 = [6.7, 6.9] I want to weave l1 into l2: [5.4, 6.5, 4.5, 7.8, 8.7] And n

Solution 1:

Your weave function drops the last element of l2; you need to use itertools.zip_longest() here:

try:
    from itertools import zip_longest
except ImportError:
    # Python 2from itertools import izip_longest as zip_longest

defweave_rows(row1, row2):
    return [v for v insum(zip_longest(row1, row2), ()) if v isnotNone]

Note that you need to return, not print, your output. The izip_longest() call adds None placeholders, which we need to remove again from the sum() output after zipping.

Now you can simply weave in a 3rd list into the output of the previous two:

weave(weave(l1, l2), l3)

Demo:

>>> weave_rows(l1, l2)
[5.4, 6.5, 4.5, 7.8, 8.7]
>>> weave_rows(weave_rows(l1, l2), l3)
[5.4, 6.7, 6.5, 6.9, 4.5, 7.8, 8.7]

Solution 2:

Another solution (based on Martijn Pieters code) which avoids recursion is:

try:
    from itertools import zip_longest
except ImportError:
    # Python 2from itertools import izip_longest as zip_longest

defweave_two(row1, row2):
    return [v for v insum(zip_longest(row1, row2, fillvalue=None), ()) if v isnotNone]

defweave_rows(*args):
    iflen(args) < 2:
        returnNone
    current = weave_two(args[0], args[1])
    for i inrange(2, len(args)):
        current = weave_two(current, args[i])
    return current

usage:

>>> weave_rows(l1, l2, l3)
[5.4, 6.7, 6.5, 6.9, 4.5, 7.8, 8.7]

Solution 3:

Function you wrote returns None, as no return statement is present. Replace print with return and chain calls. You might also need izip_longest instead of zip for lists of nonequal size:

With izip_longest:

from itertools import izip_longest
defweave(l1, l2):
    returnfilter(None, sum(izip_longest(l1, l2), ())

demo

>>> weave(weave(l1, l2), l3)
(5.4, 6.7, 6.5, 6.9, 4.5, 7.8, 8.7)

Without, zip breaks on shortest argument:

>>> defweave_shortest(l1, l2):
        returnsum(zip(l1, l2), ())
>>> weave_shortest(l3, weave_shortest(l1, l2))
(5.4, 6.7, 6.5, 6.9)

Solution 4:

OK, as peoples comments, this seems a strange case to start using classes but something like this should work:

from itertools import zip_longest

classWeaver():
    def__init__(self,data):
        self.result = data

    defweave(data):
        self.result = sum(zip_longest(self.result, data),()) # or whatever version# works best from# the other answers

w = Weaver(l1)
w.weave(l2)
w.weave(l3)
print(w.result)

This creates a Weaver object w and initialises it with l1. Then you weave the other lists in one by one and it stores the result internally and finally you access and print that result.