Scala split string to tuple

listscalasplitstringtuples

I would like to split a string on whitespace that has 4 elements:

1 1 4.57 0.83

and I am trying to convert into List[(String,String,Point)] such that first two splits are first two elements in the list and the last two is Point. I am doing the following but it doesn't seem to work:

Source.fromFile(filename).getLines.map(string => { 
            val split = string.split(" ")
            (split(0), split(1), split(2))
        }).map{t => List(t._1, t._2, t._3)}.toIterator

Best Answer

How about this:

scala> case class Point(x: Double, y: Double)
defined class Point

scala> s43.split("\\s+") match { case Array(i, j, x, y) => (i.toInt, j.toInt, Point(x.toDouble, y.toDouble)) }
res00: (Int, Int, Point) = (1,1,Point(4.57,0.83))

Related Solutions

C# – the difference between String and string in C#

string is an alias in C# for System.String.
So technically, there is no difference. It's like int vs. System.Int32.

As far as guidelines, it's generally recommended to use string any time you're referring to an object.

e.g.

string place = "world";

Likewise, I think it's generally recommended to use String if you need to refer specifically to the class.

e.g.

string greet = String.Format("Hello {0}!", place);

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C++ – How to iterate over the words of a string

I use this to split string by a delimiter. The first puts the results in a pre-constructed vector, the second returns a new vector.

#include <string>
#include <sstream>
#include <vector>
#include <iterator>

template <typename Out>
void split(const std::string &s, char delim, Out result) {
    std::istringstream iss(s);
    std::string item;
    while (std::getline(iss, item, delim)) {
        *result++ = item;
    }
}

std::vector<std::string> split(const std::string &s, char delim) {
    std::vector<std::string> elems;
    split(s, delim, std::back_inserter(elems));
    return elems;
}

Note that this solution does not skip empty tokens, so the following will find 4 items, one of which is empty:

std::vector<std::string> x = split("one:two::three", ':');

Best Answer

Related Solutions

C# – the difference between String and string in C#

This is the style that Microsoft tends to use in their examples.

C++ – How to iterate over the words of a string

Related Topic