median

问题 Can someone example the computation of median/quantiles in map reduce? My understanding of Datafu's median is that the 'n' mappers sort the data and send the data to "1" reducer which is responsible for sorting all the data from n mappers and finding the median(middle value) Is my understanding correct?, if so, does this approach scale for massive amounts of data as i can clearly see the one single reducer struggling to do the final task. Thanks 回答1: Trying to find the median (middle number)

问题 Note: Please don't interpret this as "homework question." This is just a thing I curious to know :) The median of five is sometimes used as an exercise in algorithm design and is known to be computable using only 6 comparisons . What is the best way to implement this "median of five using 6 comparisons" in C# ? All of my attempts seem to result in awkward code :( I need nice and readable code while still using only 6 comparisons. public double medianOfFive(double a, double b, double c, double

问题 I'm a programming student, and for a project I'm working on, on of the things I have to do is compute the median value of a vector of int values. I'm to do this using only the sort function from the STL and vector member functions such as .begin() , .end() , and .size() . I'm also supposed to make sure I find the median whether the vector has an odd number of values or an even number of values. And I'm Stuck , below I have included my attempt. So where am I going wrong? I would appreciate if

问题 I have a CSV file named 'salaries.csv' The content of the files is as follows: City,Job,Salary Delhi,Doctors,500 Delhi,Lawyers,400 Delhi,Plumbers,100 London,Doctors,800 London,Lawyers,700 London,Plumbers,300 Tokyo,Doctors,900 Tokyo,Lawyers,800 Tokyo,Plumbers,400 Lawyers,Doctors,300 Lawyers,Lawyers,400 Lawyers,Plumbers,500 Hong Kong,Doctors,1800 Hong Kong,Lawyers,1100 Hong Kong,Plumbers,1000 Moscow,Doctors,300 Moscow,Lawyers,200 Moscow,Plumbers,100 Berlin,Doctors,800 Berlin,Plumbers,900 Paris

问题 I am trying to find the median of each row of a 2 dimensional array. This is what I have tried so far but I cannot get it to work. Any help would be greatly appreciated. def median_rows(list): for lineindex in range(len(Matrix)): sorted(Matrix[lineindex]) mid_upper = ((len(Matrix[lineindex]))/2 mid_lower = ((len(Matrix[lineindex])+1)/2 if len(Matrix[lineindex])%2 == 0: #have to take avg of middle two median = (Matrix[mid_lower] + Matrix[mid_upper])/2.0 print "The median is %f" %median else:

问题 StackOverflow to the rescue!, I need to find the medians for five columns at once, in one query call. The median calculations below work for single columns, but when combined, multiple uses of "rownum" throws the query off. How can I update this to work for multiple columns? THANK YOU. It's to create a web tool where nonprofits can compare their financial metrics to user-defined peer groups. SELECT t1_wages.totalwages_pctoftotexp AS median_totalwages_pctoftotexp FROM ( SELECT @rownum :=

问题 I have created boxplots using ggplot2 with this code. plotgraph <- function(x, y, colour, min, max) { plot1 <- ggplot(dims, aes(x = x, y = y, fill = Region)) + geom_boxplot() #plot1 <- plot1 + scale_x_discrete(name = "Blog Type") plot1 <- plot1 + labs(color='Region') + geom_hline(yintercept = 0, alpha = 0.4) plot1 <- plot1 + scale_y_continuous(breaks=c(seq(min,max,5)), limits = c(min, max)) plot1 <- plot1 + labs(x="Blog Type", y="Dimension Score") + scale_fill_grey(start = 0.3, end = 0.7) +

问题 This is a solution for calculating the median value in an array. I get the first three lines, duh ;), but the third line is where the magic is happening. Can someone explain how the 'sorted' variable is using and why it's next to brackets, and why the other variable 'len' is enclosed in those parentheses and then brackets? It's almost like sorted is all of a sudden being used as an array? Thanks! def median(array) sorted = array.sort len = sorted.length return ((sorted[(len - 1) / 2] + sorted

问题 I'm attempting to make a procedure named median that takes the median value of a list. If the list is even, then I will return the two middle numbers. I have the logic all thought out in my head, but I'm not sure how to complete it. NOTE: I am trying to avoid using list-ref, as it would trivialize the problem. So far, my code looks like the following. (define (median lst) (if (null? lst) '() (if (even? lst) ; ends here Now, my approach to the problem is this. Odd #- Return the value of the

问题 Ok so I have a csv file similar to this structure hashID,value,flag 98fafd, 35, 1 fh56w2, 25, 0 ggjeas, 55, 1 adfh5d, 45, 0 Basically what I want to do is get the median of the value column but only include rows where flag==1 in the calculation. Is this even possible in R? I've searched around and haven't found anything like this. 回答1: Here is one possibility: Read your data set using the following command: newdata <- read.csv("stackoverflow questions/mediancol.csv") # I assume you have the