将带有两个参数的函数传递给python中的filter() [英] Passing a function with two arguments to filter() in python

问题描述

给出以下列表:

DNA_list = ['ATAT', 'GTGTACGT', 'AAAAGGTT']

我想过滤长度超过3个字符的字符串.我使用以下代码实现了这一点:

I want to filter strings longer than 3 characters. I achieve this with the following code:

具有for循环:

long_dna = []
for element in DNA_list:
    length = len(element)
    if int(length) > 3:
        long_dna.append(element)
print long_dna

但是我希望我的代码更通用，因此以后可以过滤任何长度的字符串，因此我使用了一个函数和for循环:

But I want my code to be more general, so I can later filter strings of any length, so I use a function and for loop:

def get_long(dna_seq, threshold):
    return len(dna_seq) > threshold

long_dna_loop2 = []
for element in DNA_list:
    if get_long(element, 3) is True:
        long_dna_loop2.append(element)
print long_dna_loop2

我想使用filter()实现相同的通用性，但是我无法实现.如果使用上述功能get_long()，当与filter()一起使用时，我根本无法将参数传递给它.只是不可能还是有办法解决吗?

I want to achieve the same generality using filter() but I cannot achieve this. If I use the above function get_long(), I simply cannot pass arguments to it when I use it with filter(). Is it just not possible or is there a way around it?

针对特定情况，我的代码为filter()

My code with filter() for the specific case:

def is_long(dna):
        return len(dna) > 3

    long_dna_filter = filter(is_long, DNA_list)

推荐答案

使用lambda提供阈值，如下所示:

Use lambda to provide the threshold, like this:

filter(lambda seq: get_long(seq, 3),
       dna_list)

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