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| title | localeTitle |
|---|---|
| Common Array Methods | Métodos comuns de matriz |
Métodos comuns de matriz
Ruby Arrays formam uma base fundamental na programação em Ruby, e na maioria das linguagens de fato. É usado tanto que seria benéfico conhecer e até memorizar alguns dos métodos mais usados para matrizes. Se você quiser saber mais sobre Ruby Arrays, temos um artigo sobre eles .
Para os propósitos deste guia, nosso array será o seguinte:
`` `ruby array = [0, 1, 2, 3, 4]
#### .length
The .length method tallies the number of elements in your array and returns the count:
rubi array.length => 5
#### .first
The .first method accesses the first element of the array, the element at index 0:
rubi array.first => 0
#### .last
The .last method accesses the last element of the array:
rubi array.last => 4
#### .take
The .take method returns the first n elements of the array:
rubi array.take (3) => [0, 1, 2]
#### .drop
The .drop method returns the elements after n elements of the array:
rubi array.drop (3) => [3, 4]
#### array index
You can access a specific element in an array by accessing its index. If the index does not exist in the array, nil will be returned:
rubi matriz [2] => 2
matriz [5] => nulo
#### .pop
The .pop method will permantently remove the last element of an array:
rubi array.pop => [0, 1, 2, 3]
#### .shift
The .shift method will permantently remove the first element of an array and return this element:
rubi array.shift => 0
array => [1, 2, 3, 4]
#### .push
The .push method will allow you to add an element to the end of an array:
rubi array.push (99) => [0, 1, 2, 3, 4, 99]
#### .unshift
The .unshift method will allow you to add an element to the beginning of an array:
array = [2, 3] array.unshift (1) => [1, 2, 3]
#### .delete
The .delete method removes a specified element from an array permanently:
rubi array.delete (1) => [0, 2, 3, 4]
#### .delete_at
The .delete_at method allows you to permanently remove an element of an array at a specified index:
rubi array.delete_at (0) => [1, 2, 3, 4]
#### .reverse
The .reverse method reverses the array but does not mutate it (the original array stays as is):
rubi array.reverse => [4, 3, 2, 1, 0]
#### .select
The .select method iterates over an array and returns a new array that includes any items that return true to the expression provided.
rubi array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] array.select {| number | número> 4} => [5, 6, 7, 8, 9, 10] array => [5, 6, 7, 8, 9, 10]
#### .include?
The include? method checks to see if the argument given is included in the array:
rubi array = [1, 2, 3, 4, 5] => [1, 2, 3, 4, 5] array.include? (3) = verdadeiro
.aplainar
O método flatten pode ser usado para obter uma matriz que contém matrizes aninhadas e criar uma matriz unidimensional:
`` `ruby array = [1, 2, [3, 4, 5], [6, 7]] array.flatten => [1, 2, 3, 4, 5, 6, 7]
#### .join
The .join method returns a string of all the elements of the array separated by a separator parameter. If the separator parameter is nil, the method uses an empty string as a separator between strings.
rubi array.join => "1234" array.join (" ") => "1 2 3 4"
#### .each
The .each method iterates over each element of the array, allowing you to perform actions on them.
rubi array.each do | element | coloca elemento fim => 0 1 2 3 4
#### .map
The .map method is the same as the .collect method. The .map and .collect methods iterate over each element of the array, allowing you to perform actions on them. The .map and .collect methods differ from the .each method in that they return an array containing the transformed elements.
rubi array.map {| elemento | elemento * 2} coloca elemento fim => 0 2 4 6 8
#### .uniq
The .uniq method takes in an array containing duplicate elements, and returns a copy of the array containing only unique elements--any duplicate elements are removed from the array.
rubi array = [1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 6, 7, 8] array.uniq => [1, 2, 3, 4, 5, 6, 7, 8]
#### .concat
The .concat method appends the elements from an array to the original array. The .concat method can take in multiple arrays as an argument, which will in turn append multiple arrays to the original array.
rubi array = [0, 1, 2, 3, 4] array.concat ([5, 6, 7], [8, 9, 10]) => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10] `` `