如何使用列表理解来创建斐波那契数列? [英] How can I create the fibonacci series using a list comprehension?

问题描述

我是python的新手，我想知道是否可以使用python的列表理解功能生成fibonacci系列.我不知道如何实现列表推导.我尝试了以下操作(目的是生成前五个斐波那契数):

I am new to python, and I was wondering if I could generate the fibonacci series using python's list comprehension feature. I don't know how list comprehensions are implemented. I tried the following (the intention was to generate the first five fibonacci numbers):

series=[]
series.append(1)
series.append(1)
series += [series[k-1]+series[k-2] for k in range(2,5)]

这段代码抛出错误: IndexError:列表索引超出范围.

让我知道是否有可能使用列表理解来生成这样的系列.

Let me know if it is even possible to generate such a series using a list comprehension.

推荐答案

您不能那样做:首先对列表理解进行评估，然后对该列表进行评估已添加到系列中.因此，基本上就像您写过一样:

You cannot do it like that: the list comprehension is evaluated first, and then that list is added to series. So basically it would be like you would have written:

series=[]
series.append(1)
series.append(1)
temp = [series[k-1]+series[k-2] for k in range(2,5)]
series += temp

不过，您可以通过使用 list comprehension 作为强制副作用的一种方式来解决此问题，例如:

You can however solve this by using list comprehension as a way to force side effects, like for instance:

series=[]
series.append(1)
series.append(1)
[series.append(series[k-1]+series[k-2]) for k in range(2,5)]

请注意，我们在此处不要将结果添加到系列.仅使用列表推导，以便在 series 上调用 .append .但是，有些人认为列表理解具有副作用，而更容易出错:它不是非常声明性的，并且如果不仔细地进行操作，往往会引入错误.

Note that we here do not add the result to series. The list comprehension is only used such that .append is called on series. However some consider list comprehensions with side effects rather error prone: it is not very declarative and tends to introduce bugs if not done carefully.

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