- Identify the result of method calls on arrays
- Perform simple array manipulations
In a previous lab, you learned how to create arrays and access the elements of an array. Now you are ready to manipulate arrays using different Ruby methods.
Fork and clone this lab. Run learn
to see the initial test failures, then
write the required methods in the
lib/introduction_to_simple_array_manipulation.rb
file to get the tests to
pass.
Consult the official documentation of the Ruby Language for the methods you need to use to solve the problems in this lab.
As you read the method descriptions, make sure to pay attention to understanding
what the method returns. For instance, when you call .push
on an array, it
returns the updated array:
artists = ["Hozier", "Ariana Grande", "Usher"]
next_artist = "Beyonce"
artists.push(next_artist)
# => ["Hozier", "Ariana Grande", "Usher", "Beyonce"]
However, .pop
works a little differently; it removes (and returns) the last
element from an array:
artists = ["Frida Kahlo", "Pablo Picasso", "Cai Guo-Qiang"]
artists.pop
# => "Cai Guo-Qiang"
artists
# => ["Frida Kahlo", "Pablo Picasso"]
You can see that while .pop
removes "Cai Guo-Qiang"
from the artists
array, .pop
also supplies "Cai Guo-Qiang"
as its return.
Top-tip: One of the most common problems you will encounter on your journey to becoming a software developer is not knowing what object a method returns. For example, you might assume that the result of a method call is a string but instead it is an array.
This method takes in two arguments, an Array
and a String
. It adds that
string to the end of the array using the .push
method.
This method takes in two arguments, an Array
and a String
and adds that
string to the front of the array using the .unshift
method.
This method takes in argument of an Array
and uses the .pop
method to remove
the last element from the array and return that element.
This method takes in an argument of an Array
and uses the .pop
method with an
argument of 2 to remove the last two array items and return them.
This method takes in an argument of an Array
and uses the .shift
method to
remove the first item and return it.
This method takes in an argument of an Array
and uses the .shift
method with
an argument of 2 to remove and return the first 2 items from the array.
This method takes in two arguments of two different arrays and uses the
.concat
method to add the contents of the second array to the first.
This method takes in two arguments, an Array
and a new element to be added to
the array. it uses the .insert
method to add the new element to the 4th index
of the array.
This method takes in an argument of an Array
and uses the .uniq
method to
remove any duplicate items.
This method takes in an argument of an Array
that contains other arrays and
uses the .flatten
method to return an array of strings.
This method takes in two arguments, an Array
and a String
, and uses the
.delete
method to remove any items from the array that are equal to that
string.
This method takes in two arguments, an Array
and an Integer
and deletes the
element at the index of the array that is equal to that integer.
Now that you've gotten familiar with a few of the methods that the Ruby library provides, you can perform some of the same manipulations you've been practice much more simply.