Short answer: check out how Matrix is doing it. The idea is that coerce returns [equivalent_something, equivalent_self], where equivalent_something is an object basically equivalent to something but that knows how to do operations on your Point class. In the Matrix lib, we construct a Matrix::Scalar from any Numeric object, and that class knows how to … Read more
From help(“<“): If the two arguments are atomic vectors of different types, one is coerced to the type of the other, the (decreasing) order of precedence being character, complex, numeric, integer, logical and raw. So in this case, the numeric is of lower precedence than the character. So 2 is coerced to the character “2”. … Read more
“0” is a string containing the character 0, it is not the numeric value 0. The only string-type value which evaluates to false is “”. “0” is truthy. Section 9.2 of the ECMAScript 262 specification defines how different types are converted to Boolean: Argument Type Result Undefined false Null false Boolean The result equals the … Read more
So why my explicit cast work, and the one inside .Cast<> doesn’t? Your explicit cast knows at compile time what the source and destination types are. The compiler can spot the explicit conversion, and emit code to invoke it. That isn’t the case with generic types. Note that this isn’t specific to Cast or LINQ … Read more
[T; n] is an array of length n, represented as n adjacent T instances. &[T; n] is purely a reference to that array, represented as a thin pointer to the data. [T] is a slice, an unsized type; it can only be used through some form of indirection. &[T], called a slice, is a sized … Read more
Use the names function: whatyouwant <- as.character(dd$name) names(whatyouwant) <- dd$crit as.character is necessary, because data.frame and read.table turn characters into factors with default settings. If you want a one-liner: whatyouwant <- setNames(as.character(dd$name), dd$crit)
Quoting directly from the help page for factor: To transform a factor f to its original numeric values, as.numeric(levels(f))[f] is recommended and slightly more efficient than as.numeric(as.character(f)).