>>>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 sock Added ...
>>>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 ordering is the important item to understand to get list comprehensions right. It is like a loop written backwards. To illustrate this, the following two examples produce the same result, one with a loop and the other one with a list comprehension:...
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 ...
>>> for clothing in clothes: # Iterate over the list. ... if 'sock' in clothing: # Find strings with 'sock'. ... clothes.append(clothing) # Add the sock's pair. ... print('Added a sock:', clothing) # Inform the user. ...
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() ...
# Print a file backwards f = open('somefile') forlineinreversed(list(f)): print(line, end='') 复制代码 有一个需要注意的问题就是,如果迭代对象元素很多的话,在转换成列表的过程中会耗费大量的内存。 想解决这个问题,可以在自定义类上实现__reversed__()方法来解决,代码如下: ...
# 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...
4. Iterate List using For Loop to Get Values in Backwards You can use range() function along with the len() function to get the loop iteration in the backward direction. You can specify a range with starting valuelen(list) -1, ending value-1, and incrementing value-1to help by gettin...
Note:If you need to iterate over lines in a file, it’s best to use.splitlines()only for small files. The method reads the entire file into memory, which will impact performance when you’re working with larger files. In such cases, it’s best to directlyiterate over the file objectto...