[ACCEPTED]-Python: Find the min, max value in a list of tuples-graphics
map(max, zip(*alist))
This first unzips your list, then finds 3 the max for each tuple position
>>> alist = [(1,3),(2,5),(2,4),(7,5)]
>>> zip(*alist)
[(1, 2, 2, 7), (3, 5, 4, 5)]
>>> map(max, zip(*alist))
[7, 5]
>>> map(min, zip(*alist))
[1, 3]
This will 2 also work for tuples of any length in a 1 list.
>>> from operator import itemgetter
>>> alist = [(1,3),(2,5),(2,4),(7,5)]
>>> min(alist)[0], max(alist)[0]
(1, 7)
>>> min(alist, key=itemgetter(1))[1], max(alist, key=itemgetter(1))[1]
(3, 5)
0
The zip is not necessary, so this simplifies 2 to map(max, *data) (where data is an iterator over tuples or 1 lists of the same length).
A generalized approach would be something 4 like this:
alist = [(1,6),(2,5),(2,4),(7,5)]
temp = map(sorted, zip(*alist))
min_x, max_x, min_y, max_y = temp[0][0], temp[0][-1], temp[1][0], temp[1][-1]
For Python 3, you'd need change 3 the line that createstempto:
temp = tuple(map(sorted, zip(*alist)))
The idea can be 2 abstracted into a function which works in 1 both Python 2 and 3:
from __future__ import print_function
try:
from functools import reduce # moved into functools in release 2.6
except ImportError:
pass
# readable version
def minmaxes(seq):
pairs = tuple()
for s in map(sorted, zip(*seq)):
pairs += (s[0], s[-1])
return pairs
# functional version
def minmaxes(seq):
return reduce(tuple.__add__, ((s[0], s[-1]) for s in map(sorted, zip(*seq))))
alist = [(1,6), (2,5), (2,4), (7,5)]
min_x, max_x, min_y, max_y = minmaxes(alist)
print(' '.join(['{},{}']*2).format(*minmaxes(alist))) # 1,7 4,6
triplets = [(1,6,6), (2,5,3), (2,4,9), (7,5,6)]
min_x, max_x, min_y, max_y, min_z, max_z = minmaxes(triplets)
print(' '.join(['{},{}']*3).format(*minmaxes(triplets))) # 1,7 4,6 3,9
Another solution using enumerate and list 1 comprehension
alist = [(1,3),(2,5),(2,4),(7,5)]
for num, k in enumerate(['X', 'Y']):
print 'max_%s' %k, max([i[num] for i in alist])
print 'min_%s' %k, min([i[num] for i in alist])
For python 3:
alist = [(1,3),(2,5),(2,4),(7,5)]
[x_range, y_range] = list(zip(map(min, *test_list), map(max, *alist)))
print(x_range, y_range) #prints: (1, 7) (3, 5)
Since zip/map returns an iterator 1 <object at 0x00> you need to use list()
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