How do I find numeric columns in Pandas?
Let’s say df is a pandas DataFrame. I would like to find all columns of numeric type. Something like: isNumeric = is_numeric(df) 12 Answers 12
types
How to declare a Fixed length Array in TypeScript
At the risk of demonstrating my lack of knowledge surrounding TypeScript types – I have the following question. When you make a type declaration for an array like this… position: Array<number>; …it will let you make an array with arbitrary length. However, if you want an array containing numbers with a specific length i.e. 3 … Read more
C++ auto keyword. Why is it magic?
From all the material I used to learn C++, auto has always been a weird storage duration specifier that didn’t serve any purpose. But just recently, I encountered code that used it as a type name in and of itself. Out of curiosity I tried it, and it assumes the type of whatever I happen … Read more
In Objective-C, what is the equivalent of Java’s “instanceof” keyword?
I would like to check whether an object (e.g. someObject) is assignable (cast-able) to a variable of another type (e.g. SpecifiedType). In Java, I can write: someObject instanceof SpecifiedType A related question is finding whether the runtime type of an object is equal to a another type. In Java, I can write: someObject.getClass().equals(SpecifiedType.class) How can … Read more
C# string reference type?
I know that “string” in C# is a reference type. This is on MSDN. However, this code doesn’t work as it should then: class Test { public static void Main() { string test = “before passing”; Console.WriteLine(test); TestI(test); Console.WriteLine(test); } public static void TestI(string test) { test = “after passing”; } } The output should … Read more
How to concatenate columns in a Postgres SELECT?
I have two string columns a and b in a table foo. select a, b from foo returns values a and b. However, concatenation of a and b does not work. I tried : select a || b from foo and select a||’, ‘||b from foo Update from comments: both columns are type character(2). 8 … Read more
Which data type for latitude and longitude?
I am newbie to PostgreSQL and PostGIS. I want to store latitude and longitude values in PostgreSQL 9.1.1 database table. I will calculate distance between two points, find nearer points by using this location values. Which data type should I use for latitude and longitude? 6 Answers 6
Where in memory are my variables stored in C?
By considering that the memory is divided into four segments: data, heap, stack, and code, where do global variables, static variables, constant data types, local variables (defined and declared in functions), variables (in main function), pointers, and dynamically allocated space (using malloc and calloc) get stored in memory? I think they would be allocated as … Read more
What’s the difference between size_t and int in C++?
In several C++ examples I see a use of the type size_t where I would have used a simple int. What’s the difference, and why size_t should be better? 5 Answers 5
How to get the type of a variable in MATLAB
Does MATLAB have a function/operator that indicates the type of a variable (similar to the typeof operator in JavaScript)? 6 Answers 6