uniqueidentifier

问题 I have a data frame like below. I would like to find unique rows (uniqueness). But in this data I have 'NA'. I like if all value in one row with NA value is the same with other rows (like rows: 1,2,5) I want to ignore it, but if not same (like rows : 2,4) I like to keep it as unique row. For example, in rows 1 ,2 and 6 all values except NA are the same so because NA can be value '1 and 3' I like to remove this row and just keep row 2. Also, in row 6 values 2 and 3 (exclude NA) are the same as

来源： https://stackoverflow.com/questions/26910094/is-using-system-identityhashcodeobj-reliable-to-return-unique-id

来源： https://stackoverflow.com/questions/26910094/is-using-system-identityhashcodeobj-reliable-to-return-unique-id

来源： https://stackoverflow.com/questions/1234780/turn-off-identity-insert-for-dataset-insert

问题 anyone know if there's a build in function in R that can return indices of duplicated elements corresponding to the unique elements? For instance I have a vector a <- ["A","B","B","C","C"] unique(a) will give ["A","B","C"] duplicated(a) will give [F,F,T,F,T] is there a build-in function to get a vector of indices for the same length as original vector a, that shows the location a's elements in the unique vecor (which is [1,2,2,3,3] in this example)? i.e., something like the output variable

问题 anyone know if there's a build in function in R that can return indices of duplicated elements corresponding to the unique elements? For instance I have a vector a <- ["A","B","B","C","C"] unique(a) will give ["A","B","C"] duplicated(a) will give [F,F,T,F,T] is there a build-in function to get a vector of indices for the same length as original vector a, that shows the location a's elements in the unique vecor (which is [1,2,2,3,3] in this example)? i.e., something like the output variable

问题 I've got this question. I've been working in my project (I'm also using EMF Compare). I need to keep an unique ID for each object that I'm using, that's why I decided to use the IdentityHashCode, as far as I understand, this value is the same through the compilation. I have given the object as a parameter in the method of another class, but when I try to get the hashcode this is not the same that I can see when I print the value of the object. Something like this: System.out.println("The

问题 I want to use System.Guid type as an id for all of my tables in asp.net web api application. But I also use Asp.net Identity, which using a string -type id (to store guids as well). So I wonder why is it using string id instead of System.Guid by default? And what is better choice to use through all the application - Guid id or string -guid id? In case of using string - what is the most proper and reliable way to generate new id - in code or in database? 回答1: With ASP.NET Core, you have a very

问题 Quite new to this so I hope I have the terminology in the title right. I am trying to figure out how to create an instance method that will do the following: --An ID number is returned. --As each object is created from the class constructor(instantiated?), a unique integer ID number is assigned to it. The first ID number is 1, and as new objects are instantiated, successive numbers will be assigned. I am able to find examples of class/static methods that do the above however I am unable to

问题 Quite new to this so I hope I have the terminology in the title right. I am trying to figure out how to create an instance method that will do the following: --An ID number is returned. --As each object is created from the class constructor(instantiated?), a unique integer ID number is assigned to it. The first ID number is 1, and as new objects are instantiated, successive numbers will be assigned. I am able to find examples of class/static methods that do the above however I am unable to