如果第二行以特定单词开头，则附加两行文本

Question

考虑一个包含以下内容的 .txt 文件：

Pinus ponderosa P. & C. Lawson
var. scopulorum Engelm.
[5,800] - [7,800] 9,200 ft. [May] - [Jun]. Needleleaf
evergreen tree, mesophanerophyte; nanophyll, sclerophyll.

我想附加任何以var.开头的行var. 到上一行。

这是我的代码：

with open('myfile.txt', 'r') as f:
    txt = ''
    for line in f:
        line = line.replace('\n', '')
        if next(f)[:4] == 'var.':
            txt = '{}\n{} {}'.format(txt, line, next(f))

这会引发以下错误：

Traceback (most recent call last): File "<stdin>", line 5, in <module> StopIteration

预期的输出是：

Pinus ponderosa P. & C. Lawson var. scopulorum Engelm.
[5,800] - [7,800] 9,200 ft. [May] - [Jun]. Needleleaf
evergreen tree, mesophanerophyte; nanophyll, sclerophyll.

Answer 1

您可以一次性完成，而不是在线条上进行迭代。 另外，如果您想编辑文件：

with open('myfile.txt', 'r') as f:
    txt = f.read()

txt = txt.replace('\nvar.', ' var.')

with open('myfile.txt', 'w') as f:
    f.write(txt)

Answer 2

这是一种方法。

前任：

with open(filename, 'r') as f:
    txt = ''
    for line in f:
        line = line.strip()
        if line.startswith('var.'):  #Use str.startswith
            txt += " " + line
        else:
            txt += "\n" + line

print(txt.strip())

输出：

Pinus ponderosa P. & C. Lawson var. scopulorum Engelm.
[5,800] - [7,800] 9,200 ft. [May] - [Jun]. Needleleaf
evergreen tree, mesophanerophyte; nanophyll, sclerophyll.