The mysql command line client will accept a stream of SQL statements from standard input. You can therefore pipe the output of mysqldump directly into mysql on the command line. Doing this as a cron job will regularly overwrite your test data with updated live data: mysql –user=username –password=passwd -e ‘DROP DATABASE test_db;’ mysql –user=username … Read more
Language Different programming languages will have their own flavour of bugs. C Adding debug statements can make the problem impossible to duplicate because the debug statement itself shifts pointers far enough to avoid a SEGFAULT—also known as Heisenbugs. Pointer issues are arduous to track and replicate, but debuggers can help (such as GDB and DDD). … Read more
You missed the each= argument to rep(): R> n <- 3 R> rep(1:5, each=n) [1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 R> so your example can be done with a simple R> rep(1:8, each=20)
Here’s one solution: df.expanded <- df[rep(row.names(df), df$freq), 1:2] Result: var1 var2 1 a d 2 b e 2.1 b e 3 c f 3.1 c f 3.2 c f
You can also write: [e] * n You should note that if e is for example an empty list you get a list with n references to the same list, not n independent empty lists. Performance testing At first glance it seems that repeat is the fastest way to create a list with n identical … Read more