sample

问题 Why does the rdd.sample() function on Spark RDD return a different number of elements even though the fraction parameter is the same? For example, if my code is like below: val a = sc.parallelize(1 to 10000, 3) a.sample(false, 0.1).count Every time I run the second line of the code it returns a different number not equal to 1000. Actually I expect to see 1000 every time although the 1000 elements might be different. Can anyone tell me how I can get a sample with the sample size exactly equal

问题 In some code I want to choose n random numbers in [0,1) which sum to 1 . I do so by choosing the numbers independently in [0,1) and normalizing them by dividing each one by the total sum: numbers = [random() for i in range(n)] numbers = [n/sum(numbers) for n in numbers] My "problem" is, that the distribution I get out is quite skew. Choosing a million numbers not a single one gets over 1/2 . By some effort I've calculated the pdf, and it's not nice. Here is the weird looking pdf I get for 5

问题 My machine Windows 7 Problem I'm having trouble opening samples for the Android SDK. I have successfully ran a "Hello Android". Steps I'm doing: Make new project -> Create from sample -> (some demo) Every error (except APIDemo) Could not write file: ...\Android\android-sdk\platforms\android-4\samples\LunarLander.project. Reason: Could not write file: ...\Android\android-sdk\platforms\android-4\samples\LunarLander.project. APIDemo error A project with that namespace already exists in the

问题 I'm being asked to generate a new variable based on the data from an old one. Basically, what is being asked is that I take values at random (by using the random function) from the original one and have at least 10x as many observations as the old one, and then save this as a new variable. This is my dataset: https://archive.ics.uci.edu/ml/machine-learning-databases/forest-fires/forestfires.csv The variable I wanna work with, is area This is my attempt but it is giving me a module object is

问题 I previously took a random sample of postcodes from my dataframe and then realised that I wasn't sampling across all higher level statistical units. I have around 1 million postcodes and 7000 middle output statistical units. I want the sample to have roughly the same number of postcodes from each statistical unit. How do I randomly sample 35 postcodes from each higher level statistical unit? I used the following code previously to randomly sample 250,000 postcodes: total.sample <- total

问题 Closed . This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed last year . Or I have to use straightforward way like: var arr []int for i := 0; i < 5; i++ { arr = append(arr, rand.Intn(100)) } 回答1: What you did is clean and fast enough. What you could improve on it is to pre-allocate the slice and fill it using a for.. range loop like this: s := make([]int, 5) for i :=

问题 I have created a NumericVector and I need to sample one random Integer from it. I tried to use various RcppArmarillo functions but it failed to works for me. The function is below: //#include <algorithm> #include <RcppArmadilloExtensions/sample.h> using namespace Rcpp; using namespace arma; using namespace std; int simulateNextStepC(double currentAmount, double lastPaid, int currentStatus, int currentMaturity, NumericMatrix amountLinkMatrix, NumericMatrix statusMatrix, double

问题 I have runtime errors while executing Support4Demos sample. I'm trying to launch Support4Demos sample (both on emulator and device). There are no errors in Eclipse and it's launched well. As you know first I should select category (for instance "Fragment"), then subcategory (for instance "Tabs"). And after I've selected subcategory - app crashes with following log 12-27 16:39:51.796: E/AndroidRuntime(384): FATAL EXCEPTION: main 12-27 16:39:51.796: E/AndroidRuntime(384): java.lang

问题 I am trying to take two randomly drawn subsamples from a data frame, extract the means of a column in the subsamples and calculate the difference between means. The below function and use of replicate within do.call should work as far as I can tell, but I keep getting an error message: Example data: > dput(a) structure(list(index = 1:30, val = c(14L, 22L, 1L, 25L, 3L, 34L, 35L, 36L, 24L, 35L, 33L, 31L, 30L, 30L, 29L, 28L, 26L, 12L, 41L, 36L, 32L, 37L, 56L, 34L, 23L, 24L, 28L, 22L, 10L, 19L),

问题 I'm working on a problem which is something like this : I have a table with many columns but major are DepartmentId and EmployeeIds Employee Ids Department Ids ------------------------------ A 1 B 1 C 1 D 1 AA 2 BB 2 CC 2 A1 3 B1 3 C1 3 D1 3 I want to write a SQL query such that I take out 2 sample EmployeeIds for each DepartmentID . like Employee Id Dept Ids B 1 C 1 AA 2 CC 2 D1 3 A1 3 Currently I am writing the query, select EmployeeId, DeptIds, count(*) from table_name group by 1,2 sample