... del numbers[i] # BAD: Deleting item from a list while iterating over it ... Traceback (most recent call last): File "<stdin>", line 2, in <module> IndexError: list index out of range 在遍历的时候,对列表进行删除操作,这是很低级的错误。稍微有点经验的人都不会犯。 对上面的代...
47. 修改遍历列表 >>> odd = lambda x : bool(x %2) >>> numbers = [n for n inrange(10)] >>> for i inrange(len(numbers)): ... ifodd(numbers[i]): ... del numbers[i] # BAD: Deleting item from a list while iterating over it ... Traceback (most recent call last): Fil...
for_stmt: 'for' exprlist 'in' testlist ':' suite ['else' ':' suite] Where exprlist is the assignment target. This means that the equivalent of {exprlist} = {next_value} is executed for each item in the iterable. An interesting example that illustrates this: for i in range(4):...
Before the beginning of every iteration, the next item provided by the iterator (range(4) this case) is unpacked and assigned the target list variables (i in this case). The enumerate(some_string) function yields a new value i (A counter going up) and a character from the some_string ...
It can be used toremove an item from list by it’s index. We can use it todelete the whole listas well. charList=["a","b","c","d"] delcharList[0] print(charList)# ['b', 'c', 'd'] delcharList print(charList)# NameError: name 'charList' is not defined ...
There is a way to remove an item from a list given its index instead of its value: thedelstatement. This differs from thepop()method which returns a value. Thedelstatement can also be used to remove slices from a list or clear the entire list (which we did earlier by assignment of ...
througheach itemmylistusing a copy of the list(i.e., mylist:)to avoid unexpected behavior due to modifying the list whileiterating overit. You use anif statementto check if the item is odd (i.e., not divisible by2), and if it is, you remove it from the list using theremove()...
Iterating Over a Dictionary Destructively With .popitem() Sometimes you need to iterate through a dictionary and delete its items after use. To accomplish this task, you can use the .popitem() method, which removes and returns key-value pairs from a dictionary in last-in, first-out (LIFO)...
We use the del keyword to delete an item as shown in the following example: cubes = {1:1, 2:8, 3:21, 4:64, 5:125} del cubes[5] print (cubes) Output: {1: 1, 2: 8, 3: 21, 4: 64} Delete All Elements Using the Clear() Method: We can use the clear() method, and it...
List Slicing Iterating a List Iterate along with an index number Adding elements to the list Append item at the end of the list Add item at the specified position in the list Using extend() Modify the items of a List Modify all items Removing elements from a List Remove specific item Rem...