update dict as per range of values

[DeaD_EyE]

Here a different approach. Before you must do a transformation, that all ports are in a list.

unsorted_ports = [item['port'] for item in data]

def find_port_ranges(ports):
    # the set returns only unique elements
    # then the set is sorted in reversed order
    # the resulting object is a sorted list
    ports = sorted(set(ports), reverse=True)
    # pop the last element from list, which is the smallest
    start = last = ports.pop()
    # start indicates the start range
    # last is always the value from previous iteration
    # repeat until the list ports is empty
    while ports:
        # pop the last element from list
        value = ports.pop()
        if value - 1 != last:
            yield (start, last)
            start = last = value
        else:
            # last value is current value - 1
            last = value
    # yield the last elements
    yield (start, value)

Test:

Output:
>>> example_ports = [1,2,4,3,20,10,11,13,12,21,23,28,22,25,26,29,100,101,103]
>>> list(find_port_ranges(example_ports))
[(1, 4), (10, 13), (20, 23), (25, 26), (28, 29), (100, 101), (103, 103)]

A second function can do the formatting:

def format_port_ranges(ports):
    ranges = []
    for start, end in find_port_ranges(ports):
        if start != end:
            ranges.append(f'{start}-{end}')
        else:
            ranges.append(str(start))
    return 'Ports: ' + ', '.join(ranges) # split ranges by comma

Output:
>>> format_port_ranges([1,2,3,4,10,20,11,12,13,21,22,23,22,25,26,29])                                                                                                                   
'Ports: 1-4, 10-13, 20-23, 25-26, 29'