Question

我正在尝试将file_1.txt列表中每个项目的第100个首次出现提取到新文件中。项目列表（在下面的代码中称为 target ）包含file_1.txt的第一列

file_1.txt

now:::ADV       1.48    be:::V  1.85    5488284
then:::ADV      1.44    be:::V  1.85    3994804
now:::ADV       1.48    have:::V        2.18    1760901
then:::ADV      1.44    have:::V        2.18    1099284
enough:::ADV    1.33    be:::V  1.85    928947
suppose:::V     1.37    be:::V  1.85    874407
ever:::ADV      1.48    be:::V  1.85    859428

我试过的代码在这里：

with open('file_1.txt', 'r') as infile, open('file_2.txt', 'w') as outfile:
target = []
i = 1
for line in infile:
    columns = line.split("\t")
    column_1 = columns[0]
    if column_1 not in target:
        target.append(column_1)
    for item in target:
        if line.startswith(item) and i <=100:
            outfile.write(line)
    i += 1

当然，这只是将file_1.txt的100行打印到file_2.txt。是否有一种pythonic方式一次只读取1行，将其附加到 target 并搜索100次首次出现，将其打印到file_2.txt并继续第1列中的下一个唯一单词file_1.txt？

我真的很感激任何帮助或建议。

Answer 1

如果我正确理解了您的要求，则无法在没有缓冲的情况下实现这些要求。以下方法使用字典。它基于您的代码：

with open('file_1.txt', 'r') as infile, open('file_2.txt', 'w') as outfile:
    target = {}

    for line in infile:
        columns = line.split("\t")
        column_1 = columns[0]
        try:
            target[column_1].append(line)
            if len(target[column_1]) == 100:
                for tline in target[column_1]:
                    outfile.write(tline)
                target[column_1] = None # mark word as finished
        except KeyError: # we haven't seen that word before -> start new list
            target[column_1] = [line]
        except AttributeError: # this is raised each time we try appending to None
            pass

python - 在文件列表中提取N个项目

1 个答案: