从python中的文件读取第二行的最短方法

Question

我需要从我的ascii文件的第二行创建数组。 从python文件中读取第二个非空行的最短方法是什么？ 也许通过numpy的genfromtxt？

文件示例：

hd105373_550  Alpha=12 08 36.33  Delta=+05 58 26.4  Mtime=02:04.8  Stime=12:21.3  Z=37.8  Focus=184.22
hd105373_550  Alpha=12 08 36.34  Delta=+05 58 25.7  Mtime=02:07.7  Stime=12:24.2  Z=37.8  Focus=184.22

hd105373_800  Alpha=12 08 36.34  Delta=+05 58 25.4  Mtime=02:10.1  Stime=12:26.6  Z=37.9  Focus=184.22
hd105373_800  Alpha=12 08 36.31  Delta=+05 58 25.0  Mtime=02:12.9  Stime=12:29.4  Z=37.9  Focus=184.22

Answer 1

with open('your_file') as fin:
    data = (i for i in fin if not i.isspace())
    for row in data:
        row = next(data)
        # ... do something with every second non empty row

另一种方法（在Python2上，如果文件很大，则可能要使用izip ）

with open('your_file') as fin:
    for odd, even in zip(*[(i for i in fin if not i.isspace())]*2):
        # ... do something with even

Answer 2

好吧，您可以每隔2次进行非空白操作，如下所示：

from itertools import islice

with open('your_file') as fin:
    non_blank = (line for line in fin if line.strip())
    every2 = islice(non_blank, 1, None, 2)
    for row in every2:
        # do something with row

但不确定如何从这些行中提取数据以供numpy使用（看起来像那里的一组奇怪的值）。

Answer 3

使用辅助生成器：

def only_every_second_nonempty(iterator):
    yield_next_line = False  # Set to True if lines 1, 3, 5... should be returned
    for value in iterator:
        if not value.strip(): continue  # Skip empty line
        if yield_next_line:
            yield value
        yield_next_line = not yield_next_line

现在，您可以使用类似以下内容浏览文件

with open('your_file') as f:
    for row in only_every_second_nonempty(f):
        ...