We can get the index of the first element in our list using the index() function.first_index = my_list.index('a') print(first_index) # 0As you can see, my_list.index('a') returns the index of the first element
在实际应用中,我们应该在获取数组第一个元素之前,先检查数组是否为空。 arr=[]ifarr:first_element=arr[0]print(first_element)else:print("数组为空") 1. 2. 3. 4. 5. 6. 使用函数 除了使用索引,还可以使用一些内置函数来获取数组的第一个元素。 使用list函数将数组转换为列表,然后使用[0]获取第一个...
The most straightforward way to retrieve an element from a list is by its index. In Python, list indexes start at 0, so the first element in a list has an index of 0, the second element has an index of 1, and so on. # Creating a listmy_list=[10,20,30,40,50]# Accessing the...
First, we sort the names by their first names. Then we sort the names by their last name. To do so, we split each string and choose the last string (it has index -1.) Since Python's sort algorithm is stable, the first sorting is remembered and we get the expected output. $ ./s...
In general,append()is the most efficient method for adding a single element to the end of a list.extend()is suitable for adding multiple elements from an iterable.insert()is the least efficient due to the need to shift elements to make space for the new element. The+operator creates a ...
3)第一个后代元素 :first-child mySpan = driver.find_element_by_css_selector("form :first-child") 冒号前有空格,定位到form下所有级别的第一个子元素,可定位到三个元素: mySpan = driver.find_element_by_css_selector("form input:first-child") 冒号前无空格,定位到form下所有级别的第一个input元素...
index值的是索引值,element指元素,list值我们要遍历的列表,下面看个例子。 1 2 3 my_list=['小明','小华','小天','小娜','小美','小李'] forindex,elementinenumerate(my_list): print('序号为:',index,'名字为:',element) 输出结果为:
Method-1: remove the first element of a Python list using the del statement One of the most straightforward methods to remove the first element from a Python list is to use thedelstatement in Python. Thedelstatement deletes an element at a specific index. ...
Example 1: Get Index of 3 Using for Loop & enumerate() FunctionIn this first example, we will use a for loop and the enumerate() function to get the index of the first occurrence of 3 in the list:for index, element in enumerate(my_list): if element == element_to_find: print(...
老Python带你从浅入深探究List 列表 Python中的列表(list)是最常用的数据类型之一。 Python中的列表可以存储任意类型的数据,这与其他语言中的数组(array)不同。 被存入列表中的内容可称之为元素(element)或者数据项(data item)亦或是值(value)。 虽然Python列表支持存储任意类型的数据项,但不建议这么做,事实上...