set

问题 I want count the same elements of two lists. Lists can have duplicate elements, so I can't convert this to sets and use & operator. a=[2,2,1,1] b=[1,1,3,3] set(a) & set(b) work a & b don't work It is possible to do it withoud set and dictonary? 回答1: In Python 3.x (and Python 2.7, when it's released), you can use collections.Counter for this: >>> from collections import Counter >>> list((Counter([2,2,1,1]) & Counter([1,3,3,1])).elements()) [1, 1] Here's an alternative using collections

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 3 years ago . I've noticed the table of the time complexity of set operations on the python official website. But i just wanna ask what's the time complexity of converting a list to a set, for instance, l = [1, 2, 3, 4, 5] s = set(l) I kind of know that this is actually a hash table, but how exactly does it work

问题 If anybody is familiar with Objective-C there is a collection called NSOrderedSet that acts as Set and its items can be accessed as an Array 's ones. Is there anything like this in Java? I've heard there is a collection called LinkedHashMap, but I haven't found anything like it for a set. 回答1: Take a look at LinkedHashSet class From Java doc: Hash table and linked list implementation of the Set interface, with predictable iteration order . This implementation differs from HashSet in that it

问题 I'm looking for a predicate that works as this: ?- subset([1,2,3], X). X = [] ; X = [1] ; X = [2] ; X = [3] ; X = [1, 2] ; X = [1, 2, 3] ; X = [2, 3] ; ... I've seen some subset implementations, but they all work when you want to check if one list is a subset of the another, not when you want to generate the subsets. Any ideas? 回答1: Here goes an implementation: subset([], []). subset([E|Tail], [E|NTail]):- subset(Tail, NTail). subset([_|Tail], NTail):- subset(Tail, NTail). It will generate

问题 the following script with debug option 'set -e -v' fails at the increment operator only when the variable has a prior value of zero. #!/bin/bash set -e -v i=1; let i++; echo "I am still here" i=0; let i++; echo "I am still here" i=0; ((i++)); echo "I am still here" bash (GNU bash, version 4.0.33(1)-release (x86_64-apple-darwin10) but also GNU bash, version 4.2.4(1)-release (x86_64-unknown-linux-gnu)) any ideas? 回答1: the answer to my question is not to use let (or shift , or...) but to use i=$

问题 This question already has answers here : How to remove items from a list while iterating? (30 answers) Closed 4 years ago . When I am writing code in Python, I often need to remove items from a list or other sequence type based on some criteria. I haven't found a solution that is elegant and efficient, as removing items from a list you are currently iterating through is bad. For example, you can't do this: for name in names: if name[-5:] == 'Smith': names.remove(name) I usually end up doing

问题 I would like to create a method which creates a stream of elements which are cartesian products of multiple given streams (aggregated to the same type at the end by a binary operator). Please note that both arguments and results are streams, not collections. For example, for two streams of {A, B} and {X, Y} I would like it produce stream of values {AX, AY, BX, BY} (simple concatenation is used for aggregating the strings). So far, I have came up with this code: private static <T> Stream<T>

问题 So I am trieing to copy all the style that apply on one element ( class / id / tagName / attribute etc. ). So far I found out that I can copy the computed style of an element, Just one problem ... couldend apply it on outher element ;/ or diffrend way to copy all the style. (this is as far as i got :/ ) http://jsfiddle.net/8KdJd/2/ //queriks mode + minor changes to retrive the computed style function getCS(el) { if (el.currentStyle) var y = el.currentStyle; else if (window.getComputedStyle)

问题 So I am trieing to copy all the style that apply on one element ( class / id / tagName / attribute etc. ). So far I found out that I can copy the computed style of an element, Just one problem ... couldend apply it on outher element ;/ or diffrend way to copy all the style. (this is as far as i got :/ ) http://jsfiddle.net/8KdJd/2/ //queriks mode + minor changes to retrive the computed style function getCS(el) { if (el.currentStyle) var y = el.currentStyle; else if (window.getComputedStyle)

问题 I have an ArrayList with a number of records and one column contains gas names as CO2 CH4 SO2 etc.Now i want to retrieve different gas names(unique) only without repetation from the ArrayList . How can it be done? 回答1: You should use a Set. A Set is a Collection that contains no duplicates. If you have a List that contains duplicates, you can get the unique entries like this: List<String> gasList = // create list with duplicates... Set<String> uniqueGas = new HashSet<String>(gasList); System