How can i split it into sequences/runs/subsequent-numbers, if the run is no longer than 3?
Having an array as follows
[1, 2, 3, 5, 9, 10, 16, 17, 18, 19]
My expected output would be the following arrays:
[1, 2, 3][5][9, 10][16, 17, 18][19]e.g. [[1, 2, 3], [5], [9, 10], [16, 17, 18], [19]]
If it is a run of length 8 e.g. [1, 2, 3, 4, 5, 6, 7, 8] i would like to get 8 / 3 + 1 = 2 lists:
[1, 2, 3][4, 5, 6][7, 8]If you name your current list, x and the new list of output, new_list, you can try (untested and assumes no repeat values in original list)
k = 0
new_list = [[]]
for i in range(len(x) - 1):
if x[i] not in new_list[max(k - 1, 0)]:
new_list[k].append(x[i])
for j in range(i + 1, len(x)):
if x[j] - x[i] == j - i and x[j] not in new_list[k]:
new_list[k].append(x[j])
k += 1
new_list.append([])
new_list = [x for x in new_list if x != []] # gets rid of empty list at the end
range(len(x)) instead of range(len(x) - 1)... Look for example for: x = [1, 2, 3, 5, 9, 10, 16, 17, 18, 19, 21]Here's my version that uses numpy:
import numpy as np
from itertools import chain
def split_list(mylist):
"""Function to do the initial split"""
# calculate differences
d = np.diff(mylist)
# when the differences are not 1 save that location
# we need a +1 to get make up for the lost element
breaks = list(np.arange(len(mylist) - 1)[d != 1] + 1)
slices = zip([0] + breaks, breaks + [len(mylist)])
# slice up the list
int_list = [mylist[a:b] for a, b in slices]
# chop up long sequences
chopped = [chop(l) for l in int_list]
# flatten the list once
return list(chain.from_iterable(chopped))
def chop(sublist, max_len=3):
"""Chops a list into chunks of length max_len"""
breaks = list(range(0, len(sublist), max_len))
slices = zip(breaks, breaks[1:] + [len(sublist)])
return [sublist[a:b] for a, b in slices]
Running this on the list's given:
>>> split_list([1, 2, 3, 5, 9, 10, 16, 17, 18, 19])
[[1, 2, 3], [5], [9, 10], [16, 17, 18], [19]]
Something like this?
def split_list(list, sub_list_size = 3):
sublists = []
for i in range(0, len(list), sub_list_size):
start = i
end = i + sub_list_size
sublists.append(list[start:end])
return sublists
# your list
mylist = [1,2,3,4,5,6,7,8, 9, 10, 11]
# your output
sublists = split_list(mylist)
print(sublists)
produces the following output
[[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11]]
The syntax list[start:end] will work even if end it is larger than the actual list size.
Hope this helps
