Python Variable Declaration

Okay, first things first. There is no such thing as “variable declaration” or “variable initialization” in Python. There is simply what we call “assignment”, but should probably just call “naming”. Assignment means “this name on the left-hand side now refers to the result of evaluating the right-hand side, regardless of what it referred to before … Read more

Implementing UML diagram to Java [closed]

Answer to your Question: No you dont have to use constructors, none of the classes shows one so youre fine with just the default constructors beeing generated while compiling. Here is what you can do based on the assumption that this pictures information is stored in a understandable format (like for example extracted from IBMs … Read more

What is reflection and why is it useful?

The name reflection is used to describe code which is able to inspect other code in the same system (or itself). For example, say you have an object of an unknown type in Java, and you would like to call a ‘doSomething’ method on it if one exists. Java’s static typing system isn’t really designed … Read more

How to join (merge) data frames (inner, outer, left, right)

By using the merge function and its optional parameters: Inner join: merge(df1, df2) will work for these examples because R automatically joins the frames by common variable names, but you would most likely want to specify merge(df1, df2, by = “CustomerId”) to make sure that you were matching on only the fields you desired. You … Read more

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