在python中计算列表中的值

Question

我是python的初学者，很难弄清楚我的代码有什么问题。你知道吗

我在这里要做的是将文本转换为列表中的元组，然后计算列表中的dt数。你知道吗

假设txt文件的前三行如下所示：

The/DT Fulton/NNP County/NNP Grand/NNP Jury/NNP said/VBD Friday/NNP an/DT investigation/NN of/IN Atlanta/NNP 's/POS recent/JJ primary/JJ election/NN produced/VBD ``/`` no/DT evidence/NN ''/'' that/IN any/DT irregularities/NNS took/VBD place/NN ./. 
The/DT jury/NN further/RB said/VBD in/IN term-end/JJ presentments/NNS that/IN the/DT City/NNP Executive/NNP Committee/NNP ,/, which/WDT had/VBD over-all/JJ charge/NN of/IN the/DT election/NN ,/, ``/`` deserves/VBZ the/DT praise/NN and/CC thanks/NNS of/IN the/DT City/NNP of/IN Atlanta/NNP ''/'' for/IN the/DT manner/NN in/IN which/WDT the/DT election/NN was/VBD conducted/VBN ./.
The/DT September-October/NNP term/NN jury/NN had/VBD been/VBN charged/VBN by/IN Fulton/NNP Superior/NNP Court/NNP Judge/NNP Durwood/NNP Pye/NNP to/TO investigate/VB reports/NNS of/IN possible/JJ ``/`` irregularities/NNS ''/'' in/IN the/DT hard-fought/JJ primary/NN which/WDT was/VBD won/VBN by/IN Mayor-nominate/NNP Ivan/NNP Allen/NNP Jr./NNP ./. 

保存为“练习.txt“在工作区中。你知道吗

所以我的代码如下：

with open("practice.txt") as myfile:
    for line in myfile:
        cnt += 1
        word = line.split()
        total_word_per_line += len(word)
        total_type_of_words += len(set(word))
        a = [tuple(i.split('/')) for i in word]

    for x in a:
        DT_sum = 0
        if x[1] == 'DT':
            DT_sum += 1

        total_DT_sum += DT_sum

    print total_DT_sum

但是输出显示2表示total_DT_sum，这意味着它只在第三个列表中计算DT。有没有建议把所有的DTs都算上？你知道吗

期望的输出是5（上面三句话的DT总数）

提前谢谢！你知道吗

Answer 1

您的错误：

for x in a:
    DT_sum = 0

DT_sum每次都重置为0。。。你知道吗

如果您想从头开始，最简单的方法是在每一行上使用sum的count：

with open("practice.txt") as myfile:
    nb_dt = sum(line.count("/DT") for line in my_file)

结果是13，而不是您所说的5（可以手动验证）

这个解决方案没有考虑到分词。这意味着它也会找到/DTXXX，如果有的话。你知道吗

所以更复杂一点的代码可以做到：

with open("practice.txt") as myfile:
    nb_dt = sum(1 if word.partition("/")[2]=="DT" else 0 for line in my_file for word in line.split())

每次计数1根据/拆分，每行的每个单词的右边都有DT。你知道吗

Answer 2

如果需要在计算'DT'个数之前将数据存储在元组列表中，可以使用^{}如下所示：

my_list = []

with open('practice.txt', 'r') as f:
    for line in f:
        my_list.extend([tuple(i.split('/')) for i in line.split()])

res = filter(lambda i: i[1] == 'DT', my_list)
print(len(res))  # Output: 13

^{}用于将每行的构造元组添加到my_list

^{}将只返回'DT'位于第二个位置的项。你知道吗

输出：

>>> res = filter(lambda i: i[1] == 'DT', my_list)
>>> res
[('The', 'DT'), ('an', 'DT'), ('no', 'DT'), ('any', 'DT'), ('The', 'DT'), ('the', 'DT'), ('the', 'DT'), ('the', 'DT'), ('the', 'DT'), ('the', 'DT'), ('the', 'DT'), ('The', 'DT'), ('the', 'DT')]
>>>
>>> len(res)
13