Methods for Arrays
#transpose
When called on an a 2D-array, transpose changes the columns to rows.
a = [[1,2], [3,4], [5,6]]
a.transpose
#=> [[1, 3, 5], [2, 4, 6]]
Extra: Access a column by selecting the value at each index you specify.
each {|x| x.values_at(0)}
Methods for +/- elements
#pop
#push
#slice
Methods for sorting elements
#sort
#reverse
Accumulator/ Counter methods
#inject
#reduce
Description: Shortcut methods to avoid creating a counting variable.
Change Each
#map
Definition: Perform an action on each item, output new array that is the result of the code block.
a = [ "Hello", "Bye" ]
a.map { |word| word + "!" }
#=> ["Hello!", "Bye!"]
Methods for Hashes
Looping through Keys & Values
#each_key
#each_pair
#each_value
Key-Value Conditionals
#has_key?
#has_value?
Methods for Both
Act on each element
#each
Use index to get values
#values
#values_at()
Conditional Method
#include?
Groups Based on a Filter Condition
#select, #collect, #reject
Note: collect is not a hash method.
Nested Data Structures
Access Literally
Array Example:
array[1][1][2][0]
(Index position in square brackets)
vs.
Hash Example:
hash[:outer][:inner]["almost"][3]
(key or value in square brackets)
Access by Looping
#each
For a multi-dimensional array:
array.each do |element|
element.each {|sub_element|
#codeblock
}
end
Looping in JavaScript
Looping Through Everything in an Object
for...in
for...of
for var..; range; increment
Looping through Conditionally
while
do...while