sequential-number

问题 I would like to give a sequence of numbers to a new column to a data frame. But this sequence will repeat several times based on a value in another column. (i.e It starts from 1 until that specific value will be changed to other value). My problem is how to define the ending point for each sequence in r. A part of my data frame with the column "V2" which I intend to add: V1 V2(new added column with sequential numbers) 12 1 12 2 12 3 12 4 12 5 13 1 13 2 13 3 13 4 13 5 13 6 14 1 14 2 14 3 14 4

问题 I would like to give a sequence of numbers to a new column to a data frame. But this sequence will repeat several times based on a value in another column. (i.e It starts from 1 until that specific value will be changed to other value). My problem is how to define the ending point for each sequence in r. A part of my data frame with the column "V2" which I intend to add: V1 V2(new added column with sequential numbers) 12 1 12 2 12 3 12 4 12 5 13 1 13 2 13 3 13 4 13 5 13 6 14 1 14 2 14 3 14 4

问题 When user press [Return] key then need to display the number. Like serial numbers [1,2 etc] for each line.Is there any way to do that? Following code I tried func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool { var textview_text_nssring = textView.text as NSString // Add "1" when the user starts typing into the text field if (range.location == 0 && textView.text.isEmpty ) { if text == "\n" { textView.text = "1." let cursor =

问题 Is there a managed system-level sequential number generator? DateTime.Now.Ticks won't do because the operations I'm doing sometimes occur more than once per tick. Requirement Clarifications: Process agnostic - there's really only one process that would be accessing this. Performance is critical! This is used for logging impressions on an adserver, which can reach 1k/sec It would need to be one of the following: A 4-byte sequential number that resets every tick A 12-byte sequential number -