Count number of rows per group and add result to original data frame

Using data.table: library(data.table) dt = as.data.table(df) # or coerce to data.table by reference: # setDT(df) dt[ , count := .N, by = .(name, type)] For pre-data.table 1.8.2 alternative, see edit history. Using dplyr: library(dplyr) df %>% group_by(name, type) %>% mutate(count = n()) Or simply: add_count(df, name, type) Using plyr: plyr::ddply(df, .(name, type), transform, count = … Read more

Can’t use Count() in C#

Your resource is not a list but an object. Better implementation would be something like this. [HttpGet(“{id}”)] public IActionResult Get(string id) { using (var unitOfWork = new UnitOfWork(_db)) { var r = unitOfWork.Resources.Get(id); if (r == null) { return NotFound(); } return Ok(ConvertResourceModel(r)); } }

file count of .txt Java [closed]

import java.io.File; import java.io.FilenameFilter; public class FileCountFilter { public File[] findFilesInDir(String dirName){ File dir = new File(dirName); return dir.listFiles(new FilenameFilter() { public boolean accept(File dir, String filename) { return filename.toLowerCase().endsWith(“.txt”); } } ); } } The Length of File[] returned by findFilesInDir method would be what you are looking for.

SQL QUERY COUNT THEN ADD

Its sum value by each order u will need. According to your original question orderamount <100 then add 5 WITH cte AS ( SELECT OrderID ,OrderDate ,Customer ,ProductAmount ,sum(orderamount) orderamount FROM mytable GROUP BY OrderID ,OrderDate ,Customer ,ProductAmount ) SELECT OrderID ,OrderDate ,Customer ,ProductAmount ,CASE WHEN orderamount < 100 THEN orderamount + 5 ELSE orderamount … Read more