<!-- main_leaderboard, all: [728,90][970,90][320,50][468,60] --> Python Lists ❮ Previous Next ❯ Python Collections (Arrays) There are four collection data types in the Python programming language: List is a collection which is ordered and changeable. Allows duplicate members. Tuple is a collection which is ordered and unchangeable. Allows duplicate members. Set is a collection which is unordered and unindexed. No duplicate members. Dictionary is a collection which is unordered, changeable and indexed. No duplicate members. When choosing a collection type, it is useful to understand the properties of that type. Choosing the right type for a particular data set could mean retention of meaning, and, it could mean an increase in efficiency or security. List A list is a collection which is ordered and changeable. In Python lists are written with square brackets. Example Create a List: thislist = ["apple", "banana", ...
<!-- main_leaderboard, all: [728,90][970,90][320,50][468,60] --> JavaScript Array Iteration Methods ❮ Previous Next ❯ Array iteration methods operate on every array item. Array.forEach() The forEach() method Calls a function once for each array element. Example var txt = ""; var numbers = [4, 9, 16, 25]; numbers.forEach(myFunction); function myFunction(value, index, array) { txt = txt + item + "<br>"; } Try it Yourself » Note that the function takes 3 arguments: The item value The item index The array itself Array.forEach() is not supported in Internet Explorer 8 or earlier: Method forEach() Yes 9.0 Yes Yes Yes Array.map() The map() method creates a new array by performing a function on each array element. This example multiplies each array value by 2: Example var numbers1 = [4, 9, 16, 25]; var numbers2 = numbers1.map(myFunction); function m...