sorting

问题 use List::MoreUtils 'uniq'; print join ", ", sort uniq ("b", "a", "a"); results in Argument "a" isn't numeric in sort at ... print join ", ", uniq sort ("b", "a", "a"); works as expected. print join ", ", sort {$a cmp $b} uniq ("b", "a", "a"); works too - but what is the problem with the first example? 回答1: That code falls under the sort invocation of sort SUBNAME LIST ... If SUBNAME is specified, it gives the name of a subroutine that returns an integer less than, equal to, or greater than 0

问题 Java Comparator interface - Here is an example of how Comparator works. My question is : Where is Object type o1 and o2 coming when the method compare(Object o1,Object o2) ? I don't know see any Class invoke the compare() method. I only see Collections.sort(al,new NameComparator()); Please explain, thank you. 回答1: When you call Collections.sort on any collection and pass the comparator reference , The underlying sorting method makes a call to compare method to decide which one is greater

问题 Java Comparator interface - Here is an example of how Comparator works. My question is : Where is Object type o1 and o2 coming when the method compare(Object o1,Object o2) ? I don't know see any Class invoke the compare() method. I only see Collections.sort(al,new NameComparator()); Please explain, thank you. 回答1: When you call Collections.sort on any collection and pass the comparator reference , The underlying sorting method makes a call to compare method to decide which one is greater

问题 I'm going through the tutorial intro for Python and I'm stuck on understanding a piece of code. This is from section 4.7.5 of the tutorial. pairs = [(1, 'one'), (2, 'two'), (3, 'three'), (4, 'four')] pairs.sort(key=lambda pair: pair[1]) pairs This bit of code returns [(4, 'four'), (1, 'one'), (3, 'three'), (2, 'two')] So in line one, it defines pairs with a list of different tuples. I get that. Line two is where I'm completely thrown off and I've done quite a bit of messing around with it to

问题 I have created a dictionary out of two arrays using zip() like list1 = [1,2,3,4,5] list2 = [6,7,8,9,19] dictionary1 = Dict(zip(list1,list2)) Now i want to sort this dictionary by key(list1) or by list2 . Can somebody show me a way or function, how to realize it? 回答1: Sort also takes a by keyword, which means you can do: julia> sort(collect(dictionary1), by=x->x[2]) 5-element Array{Tuple{Int64,Int64},1}: (1,6) (2,7) (3,8) (4,9) (5,19) Also note that there is a SortedDict in DataStructures.jl,

问题 For some reason, comparisons of negative floating point numbers with awk and sort seem to be broken on my machine. It seems that -0.1 < -0.2 . When I try to sort 0.2 -0.1 -0.2 0.1 0 using sort -n test.dat , I get -0.1 -0.2 0 0.1 0.2 instead of -0.2 -0.1 0 0.1 0.2 What is wrong with me? 回答1: Answer: You are French! In french, the decimal point is a comma ( , ) and not a dot ( . ). You need to either replace the dots with commas or change your locale. Try LC_NUMERIC=us_EN.UTF-8 sort -n test.dat

问题 For some reason, comparisons of negative floating point numbers with awk and sort seem to be broken on my machine. It seems that -0.1 < -0.2 . When I try to sort 0.2 -0.1 -0.2 0.1 0 using sort -n test.dat , I get -0.1 -0.2 0 0.1 0.2 instead of -0.2 -0.1 0 0.1 0.2 What is wrong with me? 回答1: Answer: You are French! In french, the decimal point is a comma ( , ) and not a dot ( . ). You need to either replace the dots with commas or change your locale. Try LC_NUMERIC=us_EN.UTF-8 sort -n test.dat

问题 I want to change the day of order presented by below code. What I want is a result with the order (Mon, Tue, Wed, Thu, Fri, Sat, Sun) - should I say, sort by key in certain predefined order? Here is my code which needs some tweak: f8 = df_toy_indoor2.groupby(['device_id', 'day'])['dwell_time'].sum() print(f8) Current result: device_id day device_112 Thu 436518 Wed 636451 Fri 770307 Tue 792066 Mon 826862 Sat 953503 Sun 1019298 device_223 Mon 2534895 Thu 2857429 Tue 3303173 Fri 3548178 Wed

问题 Imagine you were given a string and you had to sort that string alphabetically using a function. Example: sortAlphabets( 'drpoklj' ); //=> returns 'djklopr' What would be the best way to do this? 回答1: You can use array sort function: var sortAlphabets = function(text) { return text.split('').sort().join(''); }; STEPS Convert string to array Sort array Convert back array to string Demo 回答2: Newer browsers support String.prototype.localeCompare() which makes sorting utf8 encoded strings really

问题 Given an array A with n elements which starts with all 0 s and another array W also with n elements (all greater than 0 ), we want to perform the following operation repeatedly; For a given k, increment A[0], A[1], .... A[k] each by 1, and report the value of A[0]^2 * W[0] + A[1]^2 * W[1] + ... + A[n-1]^2 * W[n-1] . Looking for an O(log n) solution (per query), or faster. 来源： https://stackoverflow.com/questions/61122170/how-can-we-calculate-weighted-cumulative-sum-of-squares-with-prefix-range