#Scala filter method map series

For example, letвЂ™s say you want to add 1 to a List of numbers and then get the square of that, so turning List(1,2,3) into List(2,3,4) into List(4,9,16).

#Scala filter method map series

Using map, however, is often more convenient because you can easily chain a series of operations together. So, the for-yield expression and the map method achieve the same output, and in many cases they are pretty much equivalent. scala> for (animal val lengths = for (animal val lengthsMapped = animals.map(animal => animal.length) We can obtain the same result as foreach using a for expression. scala> animals.foreach(animal => println(animal.length)) Or, if you are performing a computation with it, like outputing the length of each element in a list of strings. Scala> animals.foreach(animal => println('She turned me into a ' + animal)) This is useful when you need to do a bit more, such as concatenating a String element with another String. scala> animals.foreach(animal => println(animal)) HereвЂ™s is how it looks in full, with a variable naming the element. This works in some cases, such as above, but wonвЂ™t always be possible. There is some underspecification going on in that we arenвЂ™t providing a variable to name elements. This says to take each element of the list (indicated by foreach) and apply a function (in this case, println) to it, in order. scala> val animals = List('newt', 'armadillo', 'cat', 'guppy')ДЄnimals: List = List(newt, armadillo, cat, guppy) But one of the most natural things to do with a list is to repeat some action for each item on the list, for example: вЂњFor each word in the given list of words: print itвЂќ. Up to now, we have (mostly) accessed individual items on a list by using their indices. (Though also, see the section on using matching in Scala in Part 3.) Iteration, the Scala way(s) This tutorial departs from the very beginner nature of the previous three, so this may be of more interest to readers who already have some programming experience in another language. Additionally you can find this and other tutorial series on the JCG Java Tutorials page.

Other posts are on this blog, and you can get links to those and other resources on the links page of the Computational Linguistics course IвЂ™m creating these for. This is part 4 of tutorials for first-time programmers getting into Scala.