Return Value from List index() Theindex()method returns the index of the given element in the list. If the element is not found, aValueErrorexception is raised. Note: Theindex()method only returns the first occurrence of the matching element. Example 1: Find the index of the element # v...
如果当前数字是偶数，将其添加到 list3。练习 3：删除和添加列表中的元素编写一个程序来删除索引 4 中的元素，并将其添加到列表的第二个位置和末尾。「提示」使用列表pop()、insert()、append()方法pop(index)：从列表中删除并返回给定索引的元素。insert(index, item)：在列表中指定位置（索引）添加元素。appen...
forindex,elementinenumerate(list): 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: 1 2 3 4 5 6 序号为...
alist[-1] # will generate an IndexError exception whereas alist[-1:] # will return an empty list astr = '' astr[-1] # will generate an IndexError exception whereas astr[-1:] # will return an empty str 1. 2. 3. 4. 5. 6. 区别在于返回空列表对象或空str对象更像是“异常元素”,...
Python内置函数___答___可以返回列表元组字典集合字符串以及range对象 python内置函数返回元素个数,一、ptthon内置函数二、内置函数详细概述2.1 abs(x):函数返回数字的绝对值。注意:1)x--数值表达式,可以是整数,浮点数,复数。2)如果参数是一个复数,则
self.length +=1# 打印顺序表defprintAllNum(self):foriinrange(self.length):print("a[%s]=%s"%(i,self.date[i]),end=" ")print("\n")# 按下标插入数据definsertNumByIndex(self,num,index):ifindex<0orindex>self.length:return0self.length +=1foriinrange(self.length-1,index,-1): ...
defis_empty(self):""" Return True if array is empty"""returnself.n==0def__len__(self):"""Return numbers of elements stored in the array."""returnself.n def__getitem__(self,i):"""Return element at index i."""ifnot0<=i<self.n:# Check it i index isinboundsofarray ...
print("First element is greater than 10.") 在这个例子中 ,如果my_list是空的,my_list and my_list[0] > 10的判断会立即停止于my_list(因为空列表在布尔上下文中为False),避免了尝试访问空列表的第一个元素而导致的IndexError。 1.2 条件赋值技巧 ...
second element of a tuple (i.e., the element at index 1)# this function is used as the key for sorting the sublistsreturnsorted(sub_li,key=itemgetter(1))# Input listsub_li=[['rishav',10],['akash',5],['ram',20],['gaurav',15]]# Printing resultant listprint(sort_tuples(sub_...
If the value is not found in the sequence, the function raises a ValueError. For example, if we have a list[1, 2, 3, 4, 5], we can find the index of the value3by callinglist.index(3), which will return the value2(since3is the third element in the list, and indexing starts ...