python - Groupby with function remembering state -

i processing many lines, want group them based on whether 1 value x in current line within 100 of value x in previous line.

for example

5, "hello" 10, "was" 60, "bla" 5000, "qwerty" 

"hello", "was" , "bla" should 1 group, "qwerty" another.

is there way neatly solve groupby? solutions can think of feel bit hackish, taking dict default argument previous value in , updating each time function (key) in groupby called.

you write simple class encapsulate temp variables, use method of class key function:

class keyclass(object):     def __init__(self):         self.lastvalue = none         self.currentkey = 1      def handleval(self, val):         if self.lastvalue not none , abs(val - self.lastvalue) > 100:             self.currentkey += 1         self.lastvalue = val         return self.currentkey  >>> [(k, list(g)) k, g in itertools.groupby(data, keyclass().handleval)] [(1, [1, 2, 100, 105]), (2, [300, 350, 375]), (3, [500]), (4, [800, 808])] 

just fun, came rather mind-bending way using send method of pre-advanced generator key function:

def keygen():     curkey = 1     newval = yield none     while true:         oldval, newval = newval, (yield curkey)         if oldval none or abs(newval-oldval) > 100:             curkey += 1  key = keygen() next(key)  >>> [(k, list(g)) k, g in itertools.groupby(data, key.send)] [(1, [1, 2, 100, 105]), (2, [300, 350, 375]), (3, [500]), (4, [800, 808])] 

wrapping head around may exercise in understanding .send (it me!).