Merging Overlapping Intervals

It makes it a bit easier to process (as in think about) if you instead setup a new list. You additionally also get to keep your original data.

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)

If you now print(merged) it would output:

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

This is a numpy solution I came up with:

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))

Output:

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

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

Please note that the input array must be sorted by start positions.