set-intersection

问题 Currently I am stuck trying to find the intersection of three sets. Now these sets are really lists that I am converting into sets, and then trying to find the intersection of. Here's what I have so far: for list1 in masterlist: list1 = thingList1 for list2 in masterlist: list2 = thingList2 for list3 in masterlist: list3 = thingList3 d3 = [set(thingList1), set(thingList2), set(thingList3)] setmatches c = set.intersection(*map(set,d3)) print setmatches and I'm getting set([]) Script terminated

问题 Is there a function that receives a list x and returns a list y such that y[[i]] = intersect(x[[1]][[i]], x[[2]][[i]], ...) ? If not, is there a R way to code it in a couple of lines? 回答1: Does this work? x <- list(list(1:3,2:4),list(2:3,4:5),list(3:7,4:5)) maxlen <- max(sapply(x,length)) lapply(seq(maxlen),function(i) Reduce(intersect,lapply(x,"[[",i))) ( intersect only takes two arguments so you have to use Reduce as an additional step) PS I haven't tried this on any hard cases -- e.g.

问题 Suppose we have: A curve described by a two-dimensional dataset that describes approximately a high order polynomial curve. A line defined by two points. This is a sample image: Supposing the line and the curve intercept each other, how could I find the intersection point between the line and the dataset? 回答1: As per my comment above import numpy as np A = np.random.random((20, 2)) A[:,0] = np.arange(20) A[:,1] = A[:,1] * (7.5 + A[:,0]) # some kind of wiggly line p0 = [-1.0,-6.5] # point 0 p1

问题 I'm trying to find the intersections between two circles in Python(using Matplotlib) but can't get any values back. I'm doing this by creating lists of X's and Y's for each individual circle(Matplotlib takes the first argument as X values and the second one as Y values when drawing a circle), and then intersecting the lists accordingly(e.g., circle1 x values with circle2 x values). import numpy import math import matplotlib.pyplot as plt import random def origin_circle(): global x_points

问题 I'm trying to find the intersections between two circles in Python(using Matplotlib) but can't get any values back. I'm doing this by creating lists of X's and Y's for each individual circle(Matplotlib takes the first argument as X values and the second one as Y values when drawing a circle), and then intersecting the lists accordingly(e.g., circle1 x values with circle2 x values). import numpy import math import matplotlib.pyplot as plt import random def origin_circle(): global x_points

问题 I'm trying to use the Mongo aggregation framework to find where there are records that have different unique sets within the same document. An example will best explain this: Here is a document that is not my real data, but conceptually the same: db.house.insert( { houseId : 123, rooms: [{ name : 'bedroom', owns : [ {name : 'bed'}, {name : 'cabinet'} ]}, { name : 'kitchen', owns : [ {name : 'sink'}, {name : 'cabinet'} ]}], uses : [{name : 'sink'}, {name : 'cabinet'}, {name : 'bed'}, {name :

问题 I assume there's no good way to do so, but if you had to, how would you implement set operations on Appengine's datastore? For example given two collections of integers, how would you store them in the datastore to get a good performance for intersect and except (all those items in A that are not in B) operations? 回答1: There aren't any built in set operations in the datastore API. I see you having two options: For smallish sets (hundreds of items) You might get away with doing keys-only

问题 I have 4 lists a <- list(1,2,3,4) b <- list(5,6,7,8) c <- list(7,9,0) d <- list(12,14) I would like to know which of the lists have elements in common. In this example, lists b and c have the element 7 in common. A brute force approach would be to take every combination of lists and find the intersection. Is there any other efficient way to do it in R? Another approach would be to make a single list from all the lists and find the duplicates. Then maybe we could have a mapping function to

问题 I am using std::set<int> and multi-set classes std::multiset<int> to perform some set operations - union, intersection etc. The problem is that I have to perform intersection between two multi-sets such that I also get the duplicate values. The intersection works fine when I use it with simple sets (not multi-sets) e.g. Set1={1,2,3,4,5,6} Set2={4,5,6,7,8,9} then the std::set_intersection give me a correct result which is {4,5,6} However, if I have a multiset multi-set1{1,1,2,2,3,3,4,4,5,5,6,6

问题 Given the following triples, are the domain and range a union or intersection or something else? <http://www.stackoverflow.com/questions/ask> rdfs:domain <http://stackoverflow.com/questions/tagged/rdf> . <http://www.stackoverflow.com/questions/ask> rdfs:domain <http://stackoverflow.com/questions/tagged/owl> . <http://www.stackoverflow.com/questions/ask> rdfs:domain <https://www.w3.org/TR/owl-ref/#Boolean> . <http://www.stackoverflow.com/questions/ask> rdfs:range <http://stackoverflow.com