英文:
Java alternative of product function of python form itertools
问题
在我的一个Java程序中，我需要使用itertools提供的product函数，对一个数组进行排列，重复k次。（ perm=itertools.product(arr,repeat=k)）。
例如，对于arr=[4,5]和k=3，输出应为：
(4, 4, 4)(4, 4, 5)(4, 5, 4)(4, 5, 5)(5, 4, 4)(5, 4, 5)(5, 5, 4)(5, 5, 5)
我想问一下，在Java中是否有任何实用工具或类似的东西可以简化这个过程？我已经在互联网上寻找过，但无法在任何地方找到。
如果您知道在这种情况下应该如何操作，请分享一些相关信息。
英文:
In one of my java program, I need to use exactly what product function from itertools offers, permuting an array reapeating k times.( perm=itertools.product(arr,repeat=k)).
for ex. for arr=[4,5] and k=3, the output should be:
(4, 4, 4)(4, 4, 5)(4, 5, 4)(4, 5, 5)(5, 4, 4)(5, 4, 5)(5, 5, 4)(5, 5, 5)
I want to ask if there is any utility or something in java which can facilitate this in java? I have been looking for it over the internet, but couldn't find it anywhere.
Please share something if you know what could be done in this case.
答案1
得分: 3
尝试一下：
我已经使用了 Python 的 itertools.product 代码作为参考。
public class Util {public static <T> List<Collection<T>> product(Collection<T> a, int r) {List<Collection<T>> result = Collections.nCopies(1, Collections.emptyList());for (Collection<T> pool : Collections.nCopies(r, new LinkedHashSet<>(a))) {List<Collection<T>> temp = new ArrayList<>();for (Collection<T> x : result) {for (T y : pool) {Collection<T> z = new ArrayList<>(x);z.add(y);temp.add(z);}}result = temp;}return result;}public static void main(String[] args) {product(List.of(4, 5), 3).forEach(System.out::println);}}
输出：
[4, 4, 4][4, 4, 5][4, 5, 4][4, 5, 5][5, 4, 4][5, 4, 5][5, 5, 4][5, 5, 5]
英文:
Try this:
I have used python itertools.product code as reference.
public class Util {public static <T> List<Collection<T>> product(Collection<T> a, int r) {List<Collection<T>> result = Collections.nCopies(1, Collections.emptyList());for (Collection<T> pool : Collections.nCopies(r, new LinkedHashSet<>(a))) {List<Collection<T>> temp = new ArrayList<>();for (Collection<T> x : result) {for (T y : pool) {Collection<T> z = new ArrayList<>(x);z.add(y);temp.add(z);}}result = temp;}return result;}public static void main(String[] args) {product(List.of(4, 5), 3).forEach(System.out::println);}}
Output:
[4, 4, 4][4, 4, 5][4, 5, 4][4, 5, 5][5, 4, 4][5, 4, 5][5, 5, 4][5, 5, 5]
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