合并重叠区间

Question

目前，我有以下间隔：

temp_tuple = [[-25, -14], [-21, -16], [-20, -15], [-10, -7], [-8, -5], [-6, -3], [2, 4], [2, 3], [3, 6], [12, 15], [13, 18], [14, 17], [22, 27], [25, 30], [26, 29]]

按下界升序排列。 我的任务是合并重叠的间隔，以便结果是：

[-25, -14]
[-10, -3]
[2, 6]
[12, 18]
[22, 30]

我的第一次尝试涉及删除完全在先前间隔内的间隔，例如 [-21, -16] 属于 [-25, -14]。 但是删除列表中的对象会不断干扰循环条件。 我第二次尝试删除不必要的间隔是：

i = 0
j = 1
while i < len(temp_tuples):
    while j < len(temp_tuples):
        if temp_tuples[i][1] > temp_tuples[j][1]:
            del temp_tuples[j]
        j += 1
    i += 1

但是出于某种原因，这并没有删除所有不必要的间隔。 我应该怎么办？

Answer 1

如果您改为设置一个新列表，它会更容易处理（如考虑）。 您还可以保留原始数据。

temp_tuple.sort(key=lambda interval: interval[0])
merged = [temp_tuple[0]]
for current in temp_tuple:
    previous = merged[-1]
    if current[0] <= previous[1]:
        previous[1] = max(previous[1], current[1])
    else:
        merged.append(current)

如果你现在print(merged)它会输出：

[[-25, -14], [-10, -3], [2, 6], [12, 18], [22, 30]]

Answer 2

这是我想出的一个 numpy 解决方案：

import numpy as np

def merge_intervals(intervals):
    starts = intervals[:,0]
    ends = np.maximum.accumulate(intervals[:,1])
    valid = np.zeros(len(intervals) + 1, dtype=np.bool)
    valid[0] = True
    valid[-1] = True
    valid[1:-1] = starts[1:] >= ends[:-1]
    return np.vstack((starts[:][valid[:-1]], ends[:][valid[1:]])).T

#example
a=[]
a.append([1,3])
a.append([4,10])
a.append([5,12])
a.append([6,8])
a.append([20,33])
a.append([30,35])

b = np.array(a)

print("intervals")
print(b)
print()
print("merged intervals")
print(merge_intervals(b))

输出：

intervals
[[ 1  3]
 [ 4 10]
 [ 5 12]
 [ 6  8]
 [20 33]
 [30 35]]

merged intervals
[[ 1  3]
 [ 4 12]
 [20 35]]

请注意，输入数组必须按起始位置排序。

Answer 3

下面解决方案的显着特征是运行一个名为final的列表与输入列表并行。 在进入for循环之前， final列表将第一个数组项插入其中。 然后开始比较。 而已！

def merger(a):

    final=[]

    final.append(a[0])

    for i in range(1,len(a)):

        if a[i][0]<=final[-1][1]:

           if a[i][1]>final[-1][1]:

               low_limit=final[-1][0]
               hi_limit=a[i][1]
               final.pop()
               final.append([low_limit,hi_limit])

           if a[i][1]<=final[-1][1]:

                low_limit=final[-1][0]
                hi_limit=final[-1][1]
                final.pop()
                final.append([low_limit,hi_limit])

          if final[-1][0]<a[i][1]<final[-1][1]:

           low_limit=a[i][0]
           hi_limit=final[-1][1]
           final.pop()
           final.append([low_limit,hi_limit])



        else:
            final.append(a[i])

    return final

if __name__=="__main__":

    array=[[-25, -14], [-21, -16], [-20, -15], [-10, -7], [-8, -5], [-6, -3], [2, 4], [2, 3], [3, 6], [12, 15], [13, 18], [14, 17], [22, 27], [25, 30], [26, 29]]
    print(merger(array))

输出：

[[-25, -14], [-10, -3], [2, 6], [12, 18], [22, 30]]

Answer 4

#Given an array of intervals in sorted order and a new interval, return a sorted array after merging the interval

def mergeinter(intervals,newinter):
    n = len(intervals)
    start = newinter[0]# we mark the start and end of the new interval to be merged
    end = newinter[1]
    right,left = 0,0
    while right < n:# we track where this new interval belongs, i.e. how many interval are to the left of it and how many are to the right
        if start <= intervals[right][1]:# we find the first interval before which it fits
            if end < intervals[right][0]:# this checks if the interval is disjoint and lies between two given intervals
                break# in this case we have nothing to do and go to line 29 directly
            start = min(start,intervals[right][0])# if it intersects with the given intervals then we just update and merge the ends
            end = max(end,intervals[right][1])
        else:# counting how many to the left continuing from line 20
            left += 1 
        right += 1# moving right to find the fit continuation of line 20 and even if we merge in line 25, we go to the next interval before
    return intervals[:left] + [(start,end)] + intervals[right:] # we return starting from the next interval

#Given a collection of intervals, merge all overlapping intervals and return sorted list of disjoint intervals.

def merge(I):
    I.sort(key:lambda i:i[0])# sorting according to the start of all intervals
    res = []# we start from the last of the given arr of lists and check the ends of the intervals and merge from the end
    for i in I:
        if not res or res[-1][0] < i[1]:# if res is empty then we put an elem in it from I
            res.append(i)# if there is no overlap, just add it
        else:
            res[-1][1] = max(i[1], res[-1][1])# here we merge from the end so that res remains sorted
    return res