count

问题 I have a model Category that has_many Pendencies . I would like to create a scope that order the categories by the amount of Pendencies that has active = true without excluding active = false . What I have so far is: scope :order_by_pendencies, -> { left_joins(:pendencies).group(:id).order('COUNT(pendencies.id) DESC')} This will order it by number of pendencies, but I want to order by pendencies that has active = true . Another try was: scope :order_by_pendencies, -> { left_joins(:pendencies)

问题 I would like to tally each time a value lies within a given range in a matrix by-row, and then sum these logical outcomes to derive a "measure of consistency" for each row. Reproducible example: m1 <- matrix(c(1,2,1,6,3,7,4,2,6,8,11,15), ncol=4, byrow = TRUE) # expected outcome, given a range of +/-1 either side exp.outcome<-matrix(c(TRUE,TRUE,TRUE,FALSE, TRUE,FALSE,TRUE,TRUE, FALSE,FALSE,FALSE,FALSE), ncol=4, byrow=TRUE) Above I've indicated the the expected outcome, in the case where each

问题 I would like to tally each time a value lies within a given range in a matrix by-row, and then sum these logical outcomes to derive a "measure of consistency" for each row. Reproducible example: m1 <- matrix(c(1,2,1,6,3,7,4,2,6,8,11,15), ncol=4, byrow = TRUE) # expected outcome, given a range of +/-1 either side exp.outcome<-matrix(c(TRUE,TRUE,TRUE,FALSE, TRUE,FALSE,TRUE,TRUE, FALSE,FALSE,FALSE,FALSE), ncol=4, byrow=TRUE) Above I've indicated the the expected outcome, in the case where each

问题 I would like to tally each time a value lies within a given range in a matrix by-row, and then sum these logical outcomes to derive a "measure of consistency" for each row. Reproducible example: m1 <- matrix(c(1,2,1,6,3,7,4,2,6,8,11,15), ncol=4, byrow = TRUE) # expected outcome, given a range of +/-1 either side exp.outcome<-matrix(c(TRUE,TRUE,TRUE,FALSE, TRUE,FALSE,TRUE,TRUE, FALSE,FALSE,FALSE,FALSE), ncol=4, byrow=TRUE) Above I've indicated the the expected outcome, in the case where each

问题 I want to add a new column to a table to record the number of attributes whose value are null for each tuple (row). How can I use SQL to get the number? for example, if a tuple is like this: Name | Age | Sex -----+-----+----- Blice| 100 | null I want to update the tuple as this: Name | Age | Sex | nNULL -----+-----+-----+-------- Blice| 100 | null| 1 Also, because I'm writing a PL/pgSQL function and the table name is obtained from argument, I don't know the schema of a table beforehand. That

问题 How to find the duplicate element in an array which is having lacks of elements? If I iterate the array for lacks of times the performance will became slow. What is the best way to iterate an array in efficient way? Or else can we use any other Java collection object to find the duplicates with less number of iterations or less time complexity? 回答1: You can use a HashSet because Sets don't allow duplicates, just loop over array of elements and insert them into a HashSet using the add() method

问题 How to find the duplicate element in an array which is having lacks of elements? If I iterate the array for lacks of times the performance will became slow. What is the best way to iterate an array in efficient way? Or else can we use any other Java collection object to find the duplicates with less number of iterations or less time complexity? 回答1: You can use a HashSet because Sets don't allow duplicates, just loop over array of elements and insert them into a HashSet using the add() method

问题 How to find the duplicate element in an array which is having lacks of elements? If I iterate the array for lacks of times the performance will became slow. What is the best way to iterate an array in efficient way? Or else can we use any other Java collection object to find the duplicates with less number of iterations or less time complexity? 回答1: You can use a HashSet because Sets don't allow duplicates, just loop over array of elements and insert them into a HashSet using the add() method

问题 Using the R programming language, I am trying to follow this tutorial over here: Count number of observations per day, month and year in R I create data at daily intervals and then took weekly sums of this data. To the "y.week" file, I want to add a "count" column that lists the number of observations in each week. Here is the code below I am using: #load libraries library(xts) library(ggplot2) #create data date_decision_made = seq(as.Date("2014/1/1"), as.Date("2016/1/1"),by="day") date

问题 I'm trying to find the amount of sentences in this table: Download Table here: http://www.mediafire.com/file/m81vtdo6bdd7bw8/Table_RandomInfoMiddle.mat/file As you can see by the full-stops, there is one sentence in column one, and 2 sentences in column 3. At the end of the day I desire to have a table with nothing but punctuation marks(with the exception of place holders like "", to keep the table rows the same length) that indicate the end of a sentence(Like "." or "?" or "!"), in order to