actually i used in this application if same color is neighbor like connected then group them
i use for segmentation of words in screen capture https://stackoverflow.com/questions/45294829/how-to-group-by-function-if-any-one-of-the-group-members-has-neighbor-relationsh i asked here too, but i do not know how to use partial and do not know what center is. On Tuesday, July 25, 2017 at 5:00:25 PM UTC+8, Peter Otten wrote: > Ho Yeung Lee wrote: > > > from itertools import groupby > > > > testing1 = [(1,1),(2,3),(2,4),(3,5),(3,6),(4,6)] > > def isneighborlocation(lo1, lo2): > > if abs(lo1[0] - lo2[0]) == 1 or lo1[1] == lo2[1]: > > return 1 > > elif abs(lo1[1] - lo2[1]) == 1 or lo1[0] == lo2[0]: > > return 1 > > else: > > return 0 > > > > groupda = groupby(testing1, isneighborlocation) > > for key, group1 in groupda: > > print key > > for thing in group1: > > print thing > > > > expect output 3 group > > group1 [(1,1)] > > group2 [(2,3),(2,4] > > group3 [(3,5),(3,6),(4,6)] > > groupby() calculates the key value from the current item only, so there's no > "natural" way to apply it to your problem. > > Possible workarounds are to feed it pairs of neighbouring items (think > zip()) or a stateful key function. Below is an example of the latter: > > $ cat sequential_group_class.py > from itertools import groupby > > missing = object() > > class PairKey: > def __init__(self, continued): > self.prev = missing > self.continued = continued > self.key = False > > def __call__(self, item): > if self.prev is not missing and not self.continued(self.prev, item): > self.key = not self.key > self.prev = item > return self.key > > def isneighborlocation(lo1, lo2): > x1, y1 = lo1 > x2, y2 = lo2 > dx = x1 - x2 > dy = y1 - y2 > return dx*dx + dy*dy <= 1 > > items = [(1,1),(2,3),(2,4),(3,5),(3,6),(4,6)] > > for key, group in groupby(items, key=PairKey(isneighborlocation)): > print key, list(group) > > $ python sequential_group_class.py > False [(1, 1)] > True [(2, 3), (2, 4)] > False [(3, 5), (3, 6), (4, 6)] -- https://mail.python.org/mailman/listinfo/python-list
