JavaScript - Why does +!{}[0] == 1?
javascript,type-conversion,coercion
You have the precedence of the operators wrong (MDN). It is: {}[0] returns undefined !undefined returns true +true returns 1...
sprintf invalid format '%d'
This is actually really interesting question. To start, %d stands for integer. The vector argument is recycled if possible but if it is c(1.5, 1) it will fail when sprintf() tries to replace %d with 1.5 (which is not integer). I thought it might be related to the fact that...
R: Kaggle Titanic Dataset Random Forest NAs introduced by coercion
You need to convert your char columns into factors. Factors are treated as integers internally whereas character fields are not. See the following small demonstration: Data: df <- data.frame(y = sample(0:1, 26, rep=T), x1=runif(26), x2=letters, stringsAsFactors=F) df$y <- as.factor(df$y) > str(df) 'data.frame': 26 obs. of 3 variables: $ y :...
JavaScript Detecting Octal Value at Different Scenario
Many JavaScript engines add octal numeric literals to the specification. The leading zero indicates octal (base 8). 2345 in base 8 (octal) is 1253 in base 10 (decimal): Octal Decimal ----- -------------------- 2 2 * 8 * 8 * 8 = 1024 3 3 * 8 * 8 = 192...
How does JS type coercion work?
"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...
What does the “by” argument in ffbase::as.character do?
r,character,optional-parameters,coercion,ffbase
Since as.character.ff works using the default as.character internally, and in view of the fact that df vectors can be larger than RAM, the data needs to be processed in chunks. The partition into chunks is facilitated by the chunk function. In this case, the relevant method is chunk.ff_vector. By default,...
Clojure casting string to double from user input
put the . on the other side of Double user> (Double. "1.22") 1.22 This calls the Double class's constructor which takes a string and produces a new double. It's syntactic sugar for (new Double "1.22")...
Why javascript console.log(1 + + “ ” + 3); sentence returns 4 and not “1 3”?
javascript,console.log,coercion
This behaviour is called coercion. In this case the unary plus operator + converts to number the expression at the right. If it cannot parse a particular value, it will evaluate to NaN. + " " //--> is coerced to 0 You can see some coercion examples in this Gist:...
What is the difference between Slice and Array
[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], also...
Why +true is not equal to true.valueOf?
the function called for evaluation is valueOf() Not always. valueOf() is only meaningful for non-primitive types, since it is defined to return the primitive value of the given object. true by itself is a Boolean primitive and as such calling true.valueOf() would be completely redundant. The unary + and...
recommended way to convert Double -> Float in Haskell
haskell,floating-point,coercion
Use realToFrac :: (Real a, Fractional b) => a -> b. It converts from any real number type (like Int, Float or Double) to any fractional type (like Float, Double or Rational). Note that even though the general definition of this function (fromRational . toRational) does a slow conversion via...