set

问题 I have this problem where I need to find the number of sums of powers that are equal to a number. So for example: An input of 100 2 would yield an output of 3 because 100 = 10^2 = 6^2 + 8^2 = 1^2 + 3^2 + 4^2 + 5^2 + 7^2 and an input of 100 3 would yield an output of 1 because 100 = 1^3 + 2^3 + 3^3 + 4^3 So my function for solving this problem is: findNums :: Int -> Int -> Int findNums a b = length [xs | xs <- (drop 1 .) subsequences [pow x b | x <- [1..c]], foldr (+) (head xs) (tail xs) == a]

问题 I have a Array of object, since I am using a 3rd party library, the array is got by calling one method from the library, I am not able to access the MyObject class . //I have no access to MyObject class, I am sure the objects contain duplicated elements. MyObject[] objects = SOME_LIB_CLASS.getObjects(); System.out.println("length is "+ objects.length); //length is 6 I try to remove duplicated elements in objects, I use Set : Set<MyObject> objectSet = new HashSet<MyObject>(Arrays.asList

问题 Given: A = [['Yes', 'lala', 'No'], ['Yes', 'lala', 'Idontknow'], ['No', 'lala', 'Yes'], ['No', 'lala', 'Idontknow']] I want to know if ['Yes', X, 'No'] exist within A, where X is anything I don't care. I attempted: valid = False for n in A: if n[0] == 'Yes' and n[2] == 'No': valid = True I know set() is useful in this type of situations. But how can this be done? Is this possible? Or is it better for me to stick with my original code? 回答1: if you want check for existance you can just ['Yes',

问题 I have dictionary of arrays as like: y_dict= {1: np.array([5, 124, 169, 111, 122, 184]), 2: np.array([1, 2, 3, 4, 5, 6, 111, 184]), 3: np.array([169, 5, 111, 152]), 4: np.array([0, 567, 5, 78, 90, 111]), 5: np.array([]), 6: np.array([])} I need to find interception of arrays in my dictionary: y_dict . As a first step I cleared dictionary from empty arrays, as like dic = {i:j for i,j in y_dict.items() if np.array(j).size != 0} So, dic has the following view: dic = { 1: np.array([5, 124, 169,

问题 I have a list with dictionaries like [{'x': 42}, {'x': 23, 'y': 5}] and want to make sure all dicts have the same keys, with values of None if the key was not present in the original dict. So the list above should become [{'x': 42, 'y': None}, {'x': 23, 'y': 5}] What's the most beautiful and pythonic way to do this? Current approach: keys = reduce(lambda k, l: k.union(set(l)), [d.keys() for d in my_list], set()) new_list = [dict.fromkeys(keys, None) for i in xrange(len(my_list))] for i, l in

问题 I am struggling with understanding what I really need to do, and would like some outside input or a point to a good reference. I have been asked to use procedural representation to "implement sets of numbers." Each set will be a one argument function that takes a number and decides if the number is in the set. A few functions (that I have read can be defined in one line) that I have to create: A function that returns a function taking a number as an argument and checks if the number is in the

问题 I am using Jackson 2.2.0 and Spring 3.2.0 with Hibernate 4.2.2. I recently had to send an array of objects via POST to the server: {"cancelationDate":"2013-06-05", "positions":[ {"price":"EUR 12.00", "count":1}, {"price":"EUR 99.00", "count":1} ] } My classes look like this: public class Bill extends { LocalDate cancelationDate; Set<Position> positions; ... } and: public class Position { Integer count; BigMoney price; @JsonIgnore Bill bill; ... } When I call bill.getPositions().size() it

问题 I am using Jackson 2.2.0 and Spring 3.2.0 with Hibernate 4.2.2. I recently had to send an array of objects via POST to the server: {"cancelationDate":"2013-06-05", "positions":[ {"price":"EUR 12.00", "count":1}, {"price":"EUR 99.00", "count":1} ] } My classes look like this: public class Bill extends { LocalDate cancelationDate; Set<Position> positions; ... } and: public class Position { Integer count; BigMoney price; @JsonIgnore Bill bill; ... } When I call bill.getPositions().size() it

问题 I am trying to do one of the most simple operations "Update" in a dynamo db list. Table Schema - businessId : String, customers: StringSet, itemCode : NumberSet I have an entry inserted via put - bussinessId = "sampleBusiness", cuatomers 0: "cust1", itemCode 0: 4554 I want to add more items using update and here is what I have tried - var updateRequest = { 'TableName' : tableName, 'Key' : { 'businessId' : { "S" : businessId } }, 'UpdateExpression' : "SET itemCode[2] =:attrValue",

问题 I want to use a collection that is sorted, but one in which I can access elements by index, i.e. I want something that has characteristics of both a Set and a List. Java.util.TreeSet comes real close to what I need, but doesn't permit access via an index. I can think of several options: I could iterate through a TreeSet every time I needed a particular element. I could maintain a TreeSet and generate a List from it when I needed to access a particular element. Same as above, only cache the