Traceback (most recent call last): File "", line 1, in ValueError: 2 is not in list 1. 2. 3. 4. 如果该项目可能不在列表中,您应该 首先检查它item in my_list(干净,可读的方法),或 将index呼叫包裹在try/except捕获的块中ValueError(可能更快,至少当搜
In this last example, we will use the index() method to get the search string in the list:try: my_list.index(search_string) print(True) except ValueError: print(False) # TrueThis example attempts to find the index of search_string within my_list using the index() method. The try ...
a.pop() removes and returns the last item in the list. (The square brackets around the i in the method signature denote that the parameter is optional, not that you should type square brackets at that position. You will see this notation frequently in the Python Library Reference....
) >>> print vendors ('Cisco', 'Juniper', 'Arista') >>> print vendors[1] Juniper >>> vendors[2] = 'Huawei' Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'tuple' object does not support item assignment 与元组有关的方法和函数 index() ...
In[1]:an_apple=27In[2]:an_example=42In[3]:an<Tab>an_apple an_example any 代码语言:javascript 代码运行次数:0 运行 AI代码解释 # 使用Tab补充变量的方法 In[3]:b=[1,2,3]In[4]:b.<Tab>append()count()insert()reverse()clear()extend()pop()sort()copy()index()remove() ...
还有就是有关于List其他的一些查找方法:1.当需要依条件来寻找集合内的某个类别时, 可用List<T>Find(), List<T>FindLast()来搜寻, 回传搜寻到的类别2.当需要依条件来寻找集合内的某些类别时, 可用List<T>FindAll()来搜寻, 将回传一个新的List<T>对象集合3.当需要依条件来寻找集合内的某个类别的索引值...
find("abc")) print(str.find("lmn")) print(str.find("n", 5, 13)) print(str.index("abc")) print(str.index("n", 5, 13)) 执行以上代码,输出结果为: Traceback (most recent call last): File ".py", line 6, in <module> print(str.index("n", 5, 13)) ^^^ ValueError: substr...
L.pop([index]) -> item -- remove andreturn item at index (default last).RaisesIndexError if list is empty or index is out of range. 1 2 3 4 5 >>> L=['shaw',12,'school',12] >>> L.pop()#(默认删除最后一个) 12 >>> L.pop(0) ...
['Test Statistic','p-value','#Lags Used','NumberofObservations Used']) for key,value in dftest[4].items(): dfoutput['CriticalValue(%s)'%key] = value return dfoutput # 自相关和偏相关图,默认阶数为31阶 def draw_acf_pacf(ts, lags=31): f = plt.figure(facecolor='white')ax1=f....
.findall('country') print(v1) # [<Element 'country' at 0x7fbdd2df7cc0>, <Element 'country' at 0x7fbdd2df7ea0>, <Element 'country' at 0x7fbdd2dfa090>] # 获取指定标签的内容 v1 = root.findall('country') for rank in v1: print(rank.find('rank').text) v2 = root.find('...