Remove cycle/repetition from list python - python
I have a list of values which might or might not have certain cycles of elements in it.
I have written below code to extract the index and length of values after that which repeats in the list. My problem is that i now have multiple index and length of values which are repeating. How to remove these elements from main list to remove those cycle
data = [1,2,3,1,2,3,4,5,6,7,4,5,6,7,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,23,18]
minrun = 1
lendata = len(data)
for runlen in range(minrun, lendata // 2):
i = 0
while i < lendata - runlen * 2:
# print("i",i)
# print("runlen", runlen)
# print(lendata - runlen * 2)
s1 = data[i:i + runlen]
# print("s1",s1)
s2 = data[i + runlen:i + runlen * 2]
# print("s2",s2)
if s1 == s2:
print(i, runlen, s1)
i += runlen
else:
i += 1
Is there a better way to do this?
This could work, but I didn't test for other sequence, I only tested it for your example.
data = [1,2,3,1,2,3,4,5,6,7,4,5,6,7,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,23,18]
print(data)
checkindex = []
for j in range(1, len(data)):
for k in range(len(data)):
try:
if data[k] == data[j+k]:
if j+k not in checkindex:
checkindex.append(j+k)
except IndexError:
continue
checkindex = sorted(checkindex)
for i in range(len(checkindex)-1, -1, -1):
del data[checkindex[i]]
print(data)
Output:
[1, 2, 3, 1, 2, 3, 4, 5, 6, 7, 4, 5, 6, 7, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 23, 18]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 23, 18]
Explanation:
for k in range(len(data)):
if data[i+k] == data[j+k]:
Basically means like this for example for j=3:
data[0] == data[3+0]: True
data[1] == data[3+1]: True
data[2] == data[3+2]: True
data[3] == data[3+3]: False
For every True, append (j+k) --> if it is not duplicate. I recommend try printing out here and there to understand more, for example:
data = [1,2,3,1,2,3,4,5,6,7,4,5,6,7,4,5,6,7,8,9,0,1,2,3,4,5,6,7,8,9,0,23,18]
print(data)
checkindex = []
for j in range(1, len(data)):
for k in range(len(data)):
try:
if data[k] == data[j+k]:
print(j, k, j+k)
if j+k not in checkindex:
checkindex.append(j+k)
except IndexError:
continue
print(checkindex)
checkindex = sorted(checkindex)
for i in range(len(checkindex)-1, -1, -1):
del data[checkindex[i]]
print(data)
Your output will be:
[1, 2, 3, 1, 2, 3, 4, 5, 6, 7, 4, 5, 6, 7, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 23, 18]
[]
[]
3 0 3
3 1 4
3 2 5
[3, 4, 5]
4 6 10
4 7 11
4 8 12
4 9 13
4 10 14
4 11 15
4 12 16
4 13 17
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17]
8 6 14
8 7 15
8 8 16
8 9 17
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17]
10 14 24
10 15 25
10 16 26
10 17 27
10 18 28
10 19 29
10 20 30
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
14 10 24
14 11 25
14 12 26
14 13 27
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30]
18 3 21
18 4 22
18 5 23
18 6 24
18 7 25
18 8 26
18 9 27
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
21 0 21
21 1 22
21 2 23
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[3, 4, 5, 10, 11, 12, 13, 14, 15, 16, 17, 24, 25, 26, 27, 28, 29, 30, 21, 22, 23]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 23, 18]
I personally think the print statement helps me understanding more.
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Python speed up permutation of bits within 32Bit number
I'm interested in reordering the bits within a number, and since I want to do it several trillion times, I want to do it fast. Here are the details: given a number num and an order matrix order. order contains up to ~6000 lines of permutations of the numbers 0..31. These are the positions to which the bits change. Simplified example: binary(num) = 1001, order[1]=[0,1,3,2], reordered number for order[1] would be 1010 (binary). Now I want to know, if my input number num is the smallest of these (~6000) reordered numbers. I'm searching for all 32-Bit numbers which fullfill this criterion. My current approach is to slow, so I'm looking for a speedup. minimal-reproducible-example: num = 1753251840 order = [[ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31], [ 3, 2, 1, 0, 7, 6, 5, 4, 11, 10, 9, 8, 15, 14, 13, 12, 19, 18, 17, 16, 23, 22, 21, 20, 27, 26, 25, 24, 31, 30, 29, 28], [15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16], [31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0], [ 0, 1, 2, 3, 4, 5, 6, 7, 16, 17, 18, 19, 20, 21, 22, 23, 8, 9, 10, 11, 12, 13, 14, 15, 24, 25, 26, 27, 28, 29, 30, 31], [21, 20, 23, 22, 29, 28, 31, 30, 17, 16, 19, 18, 25, 24, 27, 26, 5, 4, 7, 6, 13, 12, 15, 14, 1, 0, 3, 2, 9, 8, 11, 10]] patterns=set() bits = format(num, '032b') for perm in order: bitsn = [bits[perm[i]] for i in range(32)] patterns.add(int(''.join(bitsn),2)) print( min(patterns)==num) Where can I start to improve this?
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Couple of possible speed-ups, staying with Python and the current algorithm: Bail out as soon as you find a pattern less than num; once one like that is found, the condition cannot possibly be true. (You also don't need to store patterns; at most a flag whether an equal one was found, if that's not guaranteed by the problem.) bitsn could be a generator expression, and doesn't need to be in a variable; you'll have to measure whether that's faster. More fundamental improvements: If you want to find all the numbers (rather than just test a particular one), it feels like there ought to be a faster algorithm by considering what the bits mean. A couple of hours thinking could potentially let you process just the 6000 lists, rather than all 2³² integers. As others have written, if you're after pure speed, python is not the ideal language. That depends on the balance of how much time you want to spend on programming vs on running the program. Side note: Are the 32-bit integers signed or unsigned?
Python list of objects sharing reference to other objects?
I have the following code, which on first glance should produce 10 Jobs with 3 Tasks each. class Job: id = None tasks = {} class Task: id = None cnt = 0 jobs = [] for i in range(0, 10): job = Job() job.id = i for ii in range(0, 3): task = Task() task.id = cnt job.tasks[task.id] = task cnt += 1 jobs.append(job) for job in jobs: print("job {}, tasks: {}".format(job.id, job.tasks.keys())) The result is somehow surprising - we have 30 Tasks shared by each Job: job 0, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 1, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 2, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 3, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 4, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 5, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 6, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 7, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 8, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) job 9, tasks: dict_keys([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]) Can someone explain what is going on in here? UPDATE tasks is a class variable shared by all the instances.
In your Job class you need to do this class Job: id = None def __init__(self): self.tasks = {} tasks is in your class and each time you are appending to the class tasks which is shared by all the instances.
Best way to split this list into smaller lists?
I've been trying to wrap my head around the best way to split this list of numbers up that are ordered but broken up in sections. Ex: data = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 29, 30, 31, 32, 33, 35, 36, 44, 45, 46, 47] I'd like the output to be this.. sliced_data = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19],[29, 30, 31, 32, 33],[35, 36],[44, 45, 46, 47]] I've been trying a while look until it's empty but that isn't working too well.. Edit: for each_half_hour in half_hour_blocks: if next_number != each_half_hour: skippers.append(half_hour_blocks[:next_number]) del half_hour_blocks[:next_number] next_number = each_half_hour + 1
>>> data = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 29, 30, 31, 32, 33, 35, 36, 44, 45, 46, 47] >>> from itertools import groupby, count >>> [list(g) for k,g in groupby(data, key=lambda i, c=count():i-next(c))] [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19], [29, 30, 31, 32, 33], [35, 36], [44, 45, 46, 47]]
I don't see why a while-loop wouldn't work here, unless you're going for something more efficient or succinct. Something like: slice = [data.pop(0)] sliced_data = [] while data: if data[0] == slice[-1] + 1: slice.append(data.pop(0)) else: sliced_data.append(slice) slice = [data.pop(0)] sliced_data.append(slice)
How to split a list into N random-but-min-sized chunks
For example: I want to split range(37) in n=5 chunks, which each chunk having len(chunk) >= 4.
>>> def divide(lst, min_size, split_size): it = iter(lst) from itertools import islice size = len(lst) for i in range(split_size - 1,0,-1): s = random.randint(min_size, size - min_size * i) yield list(islice(it,0,s)) size -= s yield list(it) >>> list(divide(range(37), 4, 5)) [[0, 1, 2, 3], [4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22], [23, 24, 25, 26, 27], [28, 29, 30, 31], [32, 33, 34, 35, 36]] >>> list(divide(range(37), 4, 5)) [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16], [17, 18, 19, 20, 21, 22], [23, 24, 25, 26], [27, 28, 29, 30, 31], [32, 33, 34, 35, 36]] >>> list(divide(range(37), 4, 5)) [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11], [12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23], [24, 25, 26, 27, 28], [29, 30, 31, 32], [33, 34, 35, 36]] >>> list(divide(range(37), 4, 5)) [[0, 1, 2, 3, 4, 5, 6], [7, 8, 9, 10, 11, 12, 13, 14, 15, 16], [17, 18, 19, 20, 21, 22, 23, 24], [25, 26, 27, 28, 29, 30, 31], [32, 33, 34, 35, 36]] >>>
For example you could initialy set each of n chunks size to 4 and then calculate: r = (m=37 mod n), if m>=20. And then just add 1 to the first chunk and decrease r, 1 to second chunk and decrease r....and repeat until r = 0. Then you have your chunks and you can fill them.
def divide(val, num=5, minSize=4): ''' Divides val into # num chunks with each being at least of size minSize. It limits max size of a chunk using math.ceil(val/(num-len(chunks)))''' import random import math chunks = [] for i in xrange(num-1): maxSize = math.ceil(val/(num-len(chunks))) newSize = random.randint(minSize, maxSize) val = val - newSize chunks.append(newSize) chunks.append(val) return chunks Calling divide with different parameters: >>> divide(37,5,4) >>> [7, 5, 4, 10, 11] >>> divide(37,5,4) >>> [4, 5, 4, 10, 14] >>> divide(50,6,5) >>> [6, 8, 8, 5, 9, 14]