轉換號碼的清單範圍

Question

我有一串號碼，說以下內容：

1 2 3 4 6 7 8 20 24 28 32 

的信息呈現有可能在Python中表示爲範圍：

[range(1, 5), range(6, 9), range(20, 33, 4)] 

在我的輸出我會寫1..4, 6..8, 20..32..4，但這只是一個介紹問題。

Another answer顯示瞭如何在連續範圍內做到這一點。我不明白我是如何輕鬆做到這一點的。有沒有類似的技巧呢？

Answer 1

以下是對問題的簡單介紹。

def get_ranges(ls): 
    N = len(ls) 
    while ls: 
     # single element remains, yield the trivial range 
     if N == 1: 
      yield range(ls[0], ls[0] + 1) 
      break 

     diff = ls[1] - ls[0] 
     # find the last index that satisfies the determined difference 
     i = next(i for i in range(1, N) if i + 1 == N or ls[i+1] - ls[i] != diff) 

     yield range(ls[0], ls[i] + 1, diff) 

     # update variables 
     ls = ls[i+1:] 
     N -= i + 1 

Answer 2

它可能不是超短期或優雅，但它似乎工作：

def ranges(ls): 
    li = iter(ls) 
    first = next(li) 
    while True: 
     try: 
      element = next(li) 
     except StopIteration: 
      yield range(first, first+1) 
      return 
     step = element - first 
     last = element 
     while True: 
      try: 
       element = next(li) 
      except StopIteration: 
       yield range(first, last+step, step) 
       return 
      if element - last != step: 
       yield range(first, last+step, step) 
       first = element 
       break 
      last = element 

這遍歷列表的迭代器，以及收益率範圍對象：

>>> list(ranges([1, 2, 3, 4, 6, 7, 8, 20, 24, 28, 32])) 
[range(1, 5), range(6, 9), range(20, 33, 4)] 

它也處理負範圍，並且只有一個元素的範圍：

>>> list(ranges([9,8,7, 1,3,5, 99]) 
[range(9, 6, -1), range(1, 7, 2), range(99, 100)] 

Answer 3

您可以使用groupby和count從itertools模塊Counter沿collections模塊這樣的例子：

更新：見，以瞭解該解決方案及其侷限性背後的邏輯的評論。

from itertools import groupby, count 
from collections import Counter 

def ranges_list(data=list, func=range, min_condition=1): 
    # Sort in place the ranges list 
    data.sort() 

    # Find all the steps between the ranges's elements 
    steps = [v-k for k,v in zip(data, data[1:])] 

    # Find the repeated items's steps based on condition. 
    # Default: repeated more than once (min_condition = 1) 
    repeated = [item for item, count in Counter(steps).items() if count > min_condition] 

    # Group the items in to a dict based on the repeated steps 
    groups = {k:[list(v) for _,v in groupby(data, lambda n, c = count(step = k): n-next(c))] for k in repeated} 

    # Create a dict: 
    # - keys are the steps 
    # - values are the grouped elements 
    sub = {k:[j for j in v if len(j) > 1] for k,v in groups.items()} 

    # Those two lines are for pretty printing purpose: 
    # They are meant to have a sorted output. 
    # You can replace them by: 
    # return [func(j[0], j[-1]+1,k) for k,v in sub.items() for j in v] 
    # Otherwise: 
    final = [(j[0], j[-1]+1,k) for k,v in sub.items() for j in v] 
    return [func(*k) for k in sorted(final, key = lambda x: x[0])] 

ranges1 = [1, 2, 3, 4, 6, 7, 8, 20, 24, 28, 32] 
ranges2 = [1, 2, 3, 4, 6, 7, 10, 20, 24, 28, 50,51,59,60] 

print(ranges_list(ranges1)) 
print(ranges_list(ranges2)) 

輸出：

[range(1, 5), range(6, 9), range(20, 33, 4)] 
[range(1, 5), range(6, 8), range(20, 29, 4), range(50, 52), range(59, 61)] 

限制：

有了這種intput的：

ranges3 = [1,3,6,10] 
print(ranges_list(ranges3) 
print(ranges_list(ranges3, min_condition=0)) 

將輸出：

# Steps are repeated <= 1 with the condition: min_condition = 1 
# Will output an empty list 
[] 
# With min_condition = 0 
# Will output the ranges using: zip(data, data[1:]) 
[range(1, 4, 2), range(3, 7, 3), range(6, 11, 4)] 

隨意使用此解決方案並採用或修改它以滿足您的需求。

Answer 4

def ranges(data): 
    result = [] 
    if not data: 
     return result 
    idata = iter(data) 
    first = prev = next(idata) 
    for following in idata: 
     if following - prev == 1: 
      prev = following 
     else: 
      result.append((first, prev + 1)) 
      first = prev = following 
    # There was either exactly 1 element and the loop never ran, 
    # or the loop just normally ended and we need to account 
    # for the last remaining range. 
    result.append((first, prev+1)) 
    return result 

測試：

>>> data = range(1, 5) + range(6, 9) + range(20, 24) 
>>> print ranges(data) 
[(1, 5), (6, 9), (20, 24)]