Saturday, July 26, 2014

Difference between sorted, sortWith and sortBy in Scala

Scala collections provide you three options for sorting: sorted( ), sortWith( ) and sortBy( ). Here is a simplified explanation:

Will sort the list using the natural ordering (based on the implicit Ordering passed)

sortBy (an attribute)
Sort by a given attribute using the attribute's type.
e.g. given a list of Person objects, if you want to sort them in ascending order of their age (which is an Int), you could simply say: personList.sortBy(_.age)

sortWith (a function)
Takes a comparator function. Useful when you want to specify a custom sorting logic. 
e.g. if you want to sort by age descending, you could write this as: 

personList.sortWith{(leftE,rightE) => 
     leftE.age > rightE.age

Or, more simply: personList.sortWith(_.age > _.age)

Checkout this gist for a full example: