Created
February 6, 2015 19:17
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from collections import OrderedDict | |
from itertools import chain | |
class Bin(object): | |
def __init__(self, size): | |
self.size = size | |
self.item_sizes = [] | |
@property | |
def size_used(self): | |
return sum(self.item_sizes) | |
def fits(self, additional_size): | |
return (self.size_used + additional_size) <= self.size | |
def pack(self, item_size, check=True): | |
if check and not self.fits(item_size): | |
raise ValueError('item size does not fit in bin') | |
self.item_sizes.append(item_size) | |
class BinDict(OrderedDict): | |
def __init__(self, bin_sizes): | |
content = ((size, [Bin(size)]) for size in bin_sizes) | |
OrderedDict.__init__(self, content) | |
def __str__(self): | |
return '\n'.join(self.iter_lines()) | |
def iter_lines(self): | |
template = '{}x {}' | |
for size, bins in self.items(): | |
line = template.format(len(bins), size) | |
item_sizes = list( | |
chain.from_iterable(bin.item_sizes for bin in bins) | |
) | |
if item_sizes: | |
content = ', '.join(map(str, item_sizes)) | |
line = '{} ({})'.format(line, content) | |
yield line | |
def find_bin(needed_size, bin_dict): | |
for bins in bin_dict.values(): | |
for bin in bins: | |
if bin.fits(needed_size): | |
return bin | |
def get_new_bin(item_size, bin_sizes): | |
for size in bin_sizes: | |
if size >= item_size: | |
return Bin(size) | |
def get_packed_bins(item_sizes, bin_sizes): | |
bin_sizes = sorted(bin_sizes) | |
bin_dict = BinDict(bin_sizes) | |
for item_size in sorted(item_sizes, reverse=True): | |
bin = find_bin(item_size, bin_dict) | |
if bin is None: | |
bin = get_new_bin(item_size, bin_sizes) | |
if bin is None: | |
msg = 'could not find bin for item size {}' | |
raise ValueError(msg.format(item_size)) | |
bin_dict[bin.size].append(bin) | |
bin.pack(item_size, check=False) | |
return bin_dict | |
def size_dict_to_list(size_dict): | |
chained = chain.from_iterable( | |
[size] * amount for size, amount in size_dict.items() | |
) | |
return list(chained) | |
def find_lumber_combination(lumber_sizes, available_dimensions): | |
item_sizes = size_dict_to_list(lumber_sizes) | |
return get_packed_bins(item_sizes, available_dimensions) | |
def main(): | |
needed_lumber = {1470: 2, 2090: 2, 1354: 2, 1974: 1} | |
dimensions = [2000, 2500, 3000, 4000] | |
print(find_lumber_combination(needed_lumber, dimensions)) | |
if __name__ == '__main__': | |
main() |
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