python数组

Python Array contains a sequence of data. In python programming, there is no exclusive array object because we can perform all the array operations using list. Today we will learn about python array and different operations we can perform on an array (list) in python. I will assume that you have the basic idea of python variables and python data types.

Python Array包含一系列数据。 在python编程中，没有排他的数组对象，因为我们可以使用list执行所有数组操作。 今天，我们将学习python数组以及可以在python中的数组（列表）上执行的不同操作。 我将假定您具有python变量和python数据类型的基本概念。

Python数组 (Python Array)

Python supports all the array related operations through its list object. Let’s start with one-dimensional array initialization.

Python通过其list对象支持所有与数组相关的操作。 让我们从一维数组初始化开始。

Python数组示例 (Python array example)

Python array elements are defined within the brace [] and they are comma separated. The following is an example of declaring python one-dimensional array.

Python数组元素在大括号[]中定义，并且用逗号分隔。 以下是声明python一维数组的示例。

arr = [ 1, 2 ,3, 4, 5]
print (arr)
print (arr[2])
print (arr[4])

Output of above one dimensional array example program will be:

上面的一维数组示例程序的输出将是：

[1, 2, 3, 4, 5]
3
5

Array indexing starts from 0. So the value of index 2 of variable arr is 3.

数组索引从0开始。因此变量arr的索引2的值为3。

In some other programming languages such as Java, when we define an array we also need to define element type, so we are limited to store only that type of data in the array. For example, int brr[5]; is able to store integer data only.

在Java等其他编程语言中，当我们定义数组时，我们还需要定义元素类型，因此我们只能在数组中存储该类型的数据。 例如， int brr[5]; 只能存储整数数据。

But python gives us the flexibility to have the different type of data in the same array. It’s cool, right? Let’s see an example.

但是python使我们可以灵活地在同一数组中拥有不同类型的数据。 很酷吧？ 让我们来看一个例子。

student_marks = ['Akkas' , 45, 36.5]
marks = student_marks[1]+student_marks[2]
print(student_marks[0] + ' has got in total = %d + %f = %f ' % (student_marks[1], student_marks[2], marks ))

It give the following output:

它给出以下输出：

Akkas has got in total = 45 + 36.500000 = 81.500000 marks

In the above example you can see that, student_marks array have three type of data – string, int and float.

在上面的示例中，您可以看到， student_marks数组具有三种类型的数据-字符串，整数和浮点数。

Python多维数组 (Python multidimensional array)

Two dimensional array in python can be declared as follows.

python中的二维数组可以声明如下。

arr2d = [ [1,3,5] ,[2,4,6] ]
print(arr2d[0]) # prints elements of row 0
print(arr2d[1]) # prints elements of row 1
print(arr2d[1][1]) # prints element of row = 1, column = 1

It will produce the following output:

它将产生以下输出：

[1, 3, 5]                                                                                                                                                                       
[2, 4, 6]                                                                                                                                                                       
4

Similarly, we can define a three-dimensional array or multidimensional array in python.

同样，我们可以在python中定义三维数组或多维数组。

Python阵列范例 (Python array examples)

Now that we know how to define and initialize an array in python. We will look into different operations we can perform on a python array.

现在，我们知道了如何在python中定义和初始化数组。 我们将研究可以在python数组上执行的不同操作。

使用for循环遍历Python数组 (Python array traversing using for loop)

We can use for loop to traverse through elements of an array. Below is a simple example of for loop to traverse through an array.

我们可以使用for循环遍历数组的元素。 以下是for循环遍历数组的简单示例。

arrayElement = ["One", 2, 'Three' ]
for i in range(len(arrayElement)):
   print(arrayElement[i])

Below image shows the output produced by the above array example program.

下图显示了上述数组示例程序产生的输出。

使用for循环遍历2D数组 (Traversing 2D-array using for loop)

The following code print the elements row-wise then the next part prints each element of the given array.

下面的代码按行打印元素，然后下一部分打印给定数组的每个元素。

arrayElement2D = [ ["Four", 5, 'Six' ] , [ 'Good',  'Food' , 'Wood'] ]
for i in range(len(arrayElement2D)):
   print(arrayElement2D[i])

for i in range(len(arrayElement2D)):
   for j in range(len(arrayElement2D[i])):
       print(arrayElement2D[i][j])

This will output:

这将输出：

Python数组追加 (Python array append)

arrayElement = ["One", 2, 'Three' ]
arrayElement.append('Four')
arrayElement.append('Five')
for i in range(len(arrayElement)):
   print(arrayElement[i])

The new element Four and Five will be appended at the end of the array.

新元素“四”和“五”将添加到数组的末尾。

One
2
Three
Four
Five

You can also append an array to another array. The following code shows how you can do this.

您也可以将一个数组附加到另​​一个数组。 以下代码显示了如何执行此操作。

arrayElement = ["One", 2, 'Three' ]
newArray = [ 'Four' , 'Five']
arrayElement.append(newArray);
print(arrayElement)

['One', 2, 'Three', ['Four', 'Five']]

Now our one-dimensional array arrayElement turns into a multidimensional array.

现在，我们的一维数组arrayElement变成了多维数组。

Python数组大小 (Python array size)

We can use len function to determine the size of an array. Let’s look at a simple example for python array length.

我们可以使用len函数来确定数组的大小。 让我们看一个简单的python数组长度示例。

arr = ["One", 2, 'Three' ]

arr2d = [[1,2],[1,2,3,4]]

print(len(arr))
print(len(arr2d))
print(len(arr2d[0]))
print(len(arr2d[1]))

Python数组切片 (Python array slice)

Python provides a special way to create an array from another array using slice notation. Let’s look at some python array slice examples.

Python提供了一种特殊的方式来使用切片符号从另一个数组创建一个数组。 让我们看一些python数组切片示例。

arr = [1,2,3,4,5,6,7]

#python array slice

arr1 = arr[0:3] #start to index 2
print(arr1)

arr1 = arr[2:] #index 2 to end of arr
print(arr1)

arr1 = arr[:3] #start to index 2
print(arr1)

arr1 = arr[:] #copy of whole arr
print(arr1)

arr1 = arr[1:6:2] # from index 1 to index 5 with step 2
print(arr1)

Below image shows the python array slice example program output.

下图显示了python array slice示例程序输出。

Python数组插入 (Python array insert)

We can insert an element in the array using insert() function.

我们可以使用insert()函数在数组中插入一个元素。

arr = [1,2,3,4,5,6,7]

arr.insert(3,10)

print(arr)

Python数组弹出 (Python array pop)

We can call the pop function on the array to remove an element from the array at the specified index.

我们可以在数组上调用pop函数，以指定索引从数组中删除元素。

arr = [1,2,3,4,5,6,7]

arr.insert(3,10)
print(arr)

arr.pop(3)
print(arr)

That’s all about python array and different operations we can perform for the arrays in python.

这就是关于python数组以及我们可以在python中为数组执行的不同操作的全部内容。

翻译自: https://www.journaldev.com/14971/python-array

python数组