The Iterator onject starts from the first element of the collection until all the elements are accessed. The iterator can only move forward without going backwards. 迭代器有两个基本的方法:iter() 和 next(). Iterator have two basic methods: iter() and next() 字符串,列表和元组对象都可用于创...
AI代码解释 >>>clothes=['skirt','red sock']>>>forclothinginclothes:# Iterate over the list...if'sock'inclothing:# Find stringswith'sock'...clothes.append(clothing)# Add the sock's pair...print('Added a sock:',clothing)# Inform the user...Added a sock:red sock Added a sock:red ...
Let’s say we have a list of numbers and we want to check if a number is present or not. We can iterate over the list of numbers and if the number is found, break out of the loop because we don’t need to keep iterating over the remaining elements. In this case, we’ll use ...
>>>clothes = ['skirt','red sock']>>>forclothinginclothes:# Iterate over the list...if'sock'inclothing:# Find strings with 'sock'...clothes.append(clothing)# Add the sock's pair...print('Added a sock:', clothing)# Inform the user... Added a sock: red sock Added a sock: red...
# the first element of the list. # The 3rd argument of range means we iterate backwards, reducing the count # of i by 1 for i in range(n, -1, -1): heapify(nums, n, i) # Move the root of the max heap to the end of for i in range(n - 1, 0, -1): nums[i], nums[...
这段代码的可视化执行在autbor.com/iteratebackwards2进行。通过向后迭代,我们可以在列表中添加或删除条目。但是这可能很难做到正确,因为对这一基本技术的微小改变最终可能会引入错误。创建新列表比修改原始列表简单得多。正如 Python 核心开发者 Raymond Hettinger 所说: ...
#Method 1 - for item in list: for item in list: print item #Method 2 - iterate through indexes: for i in range(len(list)): print list[i] 1. 2. 3. 4. 5. 6. list的用法 - 小例子1 - string也是一种list for letter in "Codecademy": ...
# Use reversed to iterate backwards over the list of layers. for layer in reversed(layers): Y = activations.pop() # Get the activations of the last layer on the stack # Compute the error at the output layer. # The output layer error is calculated different then hidden layer error. if...
反向迭代的特点是,需要预先知道迭代对象的大小,或者对象实现了 __reversed__() 方法,如果两者都不符合,那么,必须先将对象转换成一个列表才可以。 # Print a file backwards f = open('somefile') for line in reversed(list(f)): ...
The range object is lazy. In this example, the individual numbers in the range are first referenced when you convert it to a list. Additionally, you don’t exhaust ranges when you iterate over them. You can reuse them as many times as you want....