[英]Selecting max elements from list using input value Python
I am building a program that selects max elements from a list which sums to a given input value 我正在构建一个程序,该程序从列表中选择最大元素,这些元素总和为给定的输入值
load_data = [1, 2, 3, 4, 10, 20]
eg user inputs 30
select 20 and 10
or user inputs 35
select 20, 10, 4 and 1
since they are the possible largest elements that sum up to 30
or 35
例如,用户输入
30
选择20 and 10
或者用户输入35
选择20, 10, 4 and 1
因为它们是可能合计30
或35
最大元素
code 码
def process(m):
print m
def selection():
aux = range(len(load_data))
global value # <- value is the input
while aux and value > 0:
posit = max(aux) >= value
index = aux[posit]
elem = load_data[index]
value = value - posit # <- subtract max value from input and repeat process
del aux[posit]
process(elem)
output always prints 输出总是打印
2
3
1
4
10
20
This is indeed a very complex task. 这确实是一个非常复杂的任务。 This solution only provides a basic approach.
该解决方案仅提供基本方法。 It's poor and unreviewed in eg terms of performance.
它很差,例如在性能方面没有得到审查。
import itertools
load_data = [1, 2, 3, 4, 10, 20]
maximum = 35
def selection(data, maximum):
for count in range(1,len(data)+1):
for combination in itertools.combinations(data, count):
if maximum == sum(combination):
yield combination
i = list(selection(load_data, maximum))
print (i)
And please, avoid using global variables. 并且请避免使用全局变量。 This is very bad style.
这是非常糟糕的风格。
Here you are: 这个给你:
load_data = [1, 2, 3, 4, 10, 20]
global value
value = 30
def process(m):
print m
def selection():
# make a local copy of load_data
data = load_data[:]
global value # <- value is the input
while data and (value > 0):
maxval = max(data)
posix = data.index(maxval)
if posix >=0:
value = value - data[posix] # <- subtract max value from input and repeat process
process(data[posix])
data.pop(posix)
selection()
, but as A. Grieco said, it's very simple and basic aproach to problem. ,但正如A. Grieco所说,这是解决问题的非常简单和基本的方法。
If load_data
list is constant, and always has elements from example, then you should just sort descending the load_data
first, so the bigger elements are processing first, for optimization purposes. 如果
load_data
列表是常量,并且始终包含示例中的元素,那么出于优化目的,您应该只对load_data
降序排序,因此,较大的元素首先处理。
Ie: 即:
load_data = [1, 2, 3, 4, 10, 20]
global value
value = 30
def process(m):
print m
def selection():
# make a local copy of load_data
data = sorted(load_data[:],reverse=True)
global value # <- value is the input
for v in data:
if value -v >= 0:
value -= v
process(v)
if value -v == 0:
break
selection()
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