Page 82 - DCAP310_INTRODUCTION_TO_ARTIFICIAL_INTELLIGENCE_AND_EXPERT_SYSTEMS

Introduction to Artificial Intelligence & Expert Systems

Notes Self Assessment

State whether the following statements are true or false:
10. Recursion is rarely the most efficient approach to solving a problem.
11. With recursion, you also get the added benefit that other programmers can more easily
understand.
12. A factorial of a number “x” is just the product of all integers between 0 and x.

5.5 Property Lists and Arrays

Arrays are extremely useful when you have several similar objects that you want to be able to
process the same way or to be able to process as a group rather than individually. The Array
object itself provides a number of methods that make manipulation of the whole group of
objects or specific objects within the group much easier. The following methods are provided by
Java script to assist in the manipulation of arrays:

concat(secondarray) will concatenate the elements of the second array onto the end of the
original array effectively joining two arrays together.

join(separator) converts the array into a string by placing the contents of the elements one
after the other with the specified separator in between. If no separator is specified then a
comma will be used.

pop() removes the last element from the array making the array smaller. The removed
element is returned from the method call allowing it to be processed.

push(element) adds an element to the end of the array.
reverse() reverses the order of the elements within the array.
shift() similar to pop() but removes and returns the first element in the array rather than
the last.

slice(start,end) creates a new array containing a subset of the elements from the original
array. The start and end values are numbers indicating which elements to extract counting
from the start of the array if the numbers are positive or from the end of the array if they
are negative. If an end value is omitted then the elements from the start position to the end
of the array will be extracted.
sort(compareFunction) will sort the elements in the array into any desired order. If no
compare function is specified then the elements will be treated as strings and sorted into
ascending order. By providing an appropriate compare function you can set whatever sort
order you require.

splice(position,number,element1,...) allows you to insert, delete, or replace elements from
anywhere within the array. The specified number of elements from the specified position
will be removed from the array and will be replaced with the elements specified in the
third and subsequent parameters.

unshift(element) similar to push except that the new element gets added to the start rather
than the end of the array.
All of the above methods can be used for conventional arrays where the elements of the arrays
are numbered. Such conventional arrays also have a length property that can be used to determine
the number of elements that are currently allocated to the array. There is a second type of array
known as an associative array where the elements of the array are named rather than numbered.

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