unique

问题 Given an STL vector, output only the duplicates in sorted order, e.g., INPUT : { 4, 4, 1, 2, 3, 2, 3 } OUTPUT: { 2, 3, 4 } The algorithm is trivial, but the goal is to make it as efficient as std::unique(). My naive implementation modifies the container in-place: My naive implementation: void not_unique(vector<int>* pv) { if (!pv) return; // Sort (in-place) so we can find duplicates in linear time sort(pv->begin(), pv->end()); vector<int>::iterator it_start = pv->begin(); while (it_start !=

问题 I have an ASCII text file. I want to generate a list of all "words" from that file using one or more Ubuntu commands. A word is defined as an alpha-num sequence between delimiters. Delimiters are by default whitespaces but I also want to experiment with other characters like punctuation etc. IN other words, i want to be able to specify a delimiter char set. How do I produce only a unique set of words? What if I also want to list only those words that are at least N characters long? 回答1: You

问题 I would like to know if there is an implicit SELECT being run prior to performing an INSERT on a table that has any column defined as UNIQUE. I cannot find anything about this in the documentation for INSERT. I have asked some other questions that nobody seems to be able to answer - perhaps because I'm not properly explaining myself - that are related to the above question. If I understand correctly, then I assume the following would be true: CASE 1: You have a table with 1 billion rows. Each

问题 I have a data frame that looks like this: date time id datetime 1 2015-01-02 14:27:22.130 999000000007628 2015-01-02 14:27:22 2 2015-01-02 14:41:27.720 989001002807730 2015-01-02 14:41:27 3 2015-01-02 14:41:27.940 989001002807730 2015-01-02 14:41:27 4 2015-01-02 14:41:28.140 989001002807730 2015-01-02 14:41:28 5 2015-01-02 14:41:28.170 989001002807730 2015-01-02 14:41:28 6 2015-01-02 14:41:28.350 989001002807730 2015-01-02 14:41:28 I need to find the number of unique "id"s for each "date" in

问题 I have a dataframe Data: Data <- data.frame(A=sample(1:7),B=c(5,5,5,6,6,6,6),C=c(1,2,2,3,3,4,5)) A B C 1 6 5 1 2 7 5 2 3 4 5 2 4 2 6 3 5 1 6 3 6 5 6 4 7 3 6 5 I am trying to extract the unique values from each of the columns into a data.frame. Each column has a different set and number of unique values. I am looking for something like: A 1 2 3 4 5 6 7 B 5 6 NA NA NA NA NA C 1 2 3 4 5 NA NA I was able to loop through it and get a list with the information (I tried using a list because they are

问题 I hope this is not a duplicate question, but if it is, feel free to point me in the right direction. I have a vector<vector<int> > . Is it possible to use unique() on this? Something like: vector<vector<int> > myvec; //blah blah do something to myvec vector<vector<int> >::interator it = unique(myvec.begin(), myvec.end()); Would the range myvec.begin() to it be unique? 回答1: Yes, as long as your vector is sorted. See unique () STL documentation for details. Here is an example of usage: #include

问题 This question already has answers here : Frequency table for a single variable (3 answers) Closed 2 years ago . I have a dataframe and I am looking at one column within the dataframe called names array(['Katherine', 'Robert', 'Anne', nan, 'Susan', 'other'], dtype=object) I am trying to make a call to tell me how many times each of these unique names shows up in the column, for example if there are 223 instances of Katherine etc. How do i do this? i know value_counts just shows 1 for each of

问题 Disclaimer: this was a homework problem. The deadline has passed now, so discussions can continue without needing to worry about that. The problem I'm struggling with is to determine whether a particular minimum s-t cut in a graph G = (V, E) is unique. It's simple enough to find some min-cut using a max-flow algorithm as per this example, but how would you show it's the min-cut? 回答1: Ok, since you don't want the whole answer right away, I'm gonna give you a few hints. Read as many as you feel

问题 Disclaimer: this was a homework problem. The deadline has passed now, so discussions can continue without needing to worry about that. The problem I'm struggling with is to determine whether a particular minimum s-t cut in a graph G = (V, E) is unique. It's simple enough to find some min-cut using a max-flow algorithm as per this example, but how would you show it's the min-cut? 回答1: Ok, since you don't want the whole answer right away, I'm gonna give you a few hints. Read as many as you feel

问题 I'm writing a program that will print the unique character in a string (entered through a scanner). I've created a method that tries to accomplish this but I keep getting characters that are not repeats, instead of a character (or characters) that is unique to the string. I want the unique letters only. Here's my code: import java.util.Scanner; public class Sameness{ public static void main (String[]args){ Scanner kb = new Scanner (System.in); String word = ""; System.out.println("Enter a