我需要从文件中过滤或删除一些行

Question

这是输入文件，它的结构已经正确：

Name:  mr. Apple
class:  class 1
sub:  subject 1
ContactNo: 11111
Name:  mr. ball
class:  class  2
sub:  subject  2
ContactNo: 2222
Name:  mr. cat
class:  class 3
sub:  subject 3
ContactNo: 33333
class:  class 4
sub:  subject 4
ContactNo:44444
class:  class 5
sub:  subject 5
ContactNo: 55555
Name:  mr. tom
class:  class 9
sub:  subject 9
ContactNo: 99999

如您所见，有些细节没有名字。

例如： 等级：4级 子：主题4 联系电话：44444

我需要删除这些，只保留那些有名字的人的详细信息。

预期输出：

Name:  mr. Apple
class:  class 1
sub:  subject 1
ContactNo: 11111
Name:  mr. ball
class:  class  2
sub:  subject  2
ContactNo: 2222
Name:  mr. cat
class:  class 3
sub:  subject 3
ContactNo: 33333
Name:  mr. tom
class:  class 9
sub:  subject 9
ContactNo: 99999

我试过了：

errors = []                       # The list where we will store results.
linenum = 0
substr = "Name:".lower()          # Substring to search for.
substr1 = "class:".lower()
substr2 = "sub:".lower()
substr3 = "ContactNo:".lower()

with open ('scrap.txt', 'rt') as myfile:
    for line in myfile:
        linenum += 1
        if line.lower().find(substr) != -1:    # if case-insensitive match,
            errors.append(line)
        elif  line.lower().find(substr1) != -1:        
            errors.append(line)
        elif  line.lower().find(substr2) != -1:     
            errors.append(line)
        elif  line.lower().find(substr3) != -1:      
            errors.append(line)

for err in errors:
    fp = open("rawextract.txt","a")
    fp.write(err)
    fp.close()
    print(err)

但我不知道如何丢弃不完整的行。

Answer 1

您可以将re.findall 与匹配正确结构的预期标头序列的正则表达式模式一起使用：

import re
with open('scrap.txt') as myfile:
    for m in re.findall('Name:.*\nclass:.*\nsub:.*\nContactNo:.*', myfile.read()):
        print(m)

这个输出：

Name:  mr. Apple
class:  class 1
sub:  subject 1
ContactNo: 11111
Name:  mr. ball
class:  class  2
sub:  subject  2
ContactNo: 2222
Name:  mr. cat
class:  class 3
sub:  subject 3
ContactNo: 33333
Name:  mr. tom
class:  class 9
sub:  subject 9
ContactNo: 99999

Answer 2

你可以创建一个无穷无尽的迭代

['name:', 'class:', 'sub:', 'concatno:', 'name:', 'class:', ...]

使用itertools.cycle。

然后检查该行是否包含下一个值，如果是，则将其写入结果，否则跳过它：

创建数据文件：

with open("f.txt","w") as f:
    f.write("""
Name:  mr. Apple
class:  class 1
sub:  subject 1
ContactNo: 11111
Name:  mr. ball
class:  class  2
sub:  subject  2
ContactNo: 2222
Name:  mr. cat
class:  class 3
sub:  subject 3
ContactNo: 33333
Name:  mr. tom
class:  class 9
sub:  subject 9
ContactNo: 99999
""")

计划：

from itertools import cycle
order = ["name:","class:","sub:","contactno:"]
t = cycle(order)

nxt = next(t) # name: 
with open("f.txt") as f, open("mod.txt","w") as writer:
    for line in f:
        if nxt in line.lower():
            writer.write(line)
            nxt = next(t)       # advance to the next thing to be read

print(open("mod.txt").read())

输出：

Name:  mr. Apple
class:  class 1
sub:  subject 1
ContactNo: 11111
Name:  mr. ball
class:  class  2
sub:  subject  2
ContactNo: 2222
Name:  mr. cat
class:  class 3
sub:  subject 3
ContactNo: 33333
Name:  mr. tom
class:  class 9
sub:  subject 9
ContactNo: 99999

如果您的有效数据跳过了其中应包含的部分内容，这将失败：

Name:  mr. tom    # taken
class:  class 9   # taken
sub:  subject 9   # taken, no contact number follows
Name:  mr. tom    # skipped
class:  class 9   # skipped
sub:  subject 9   # skipped
ContactNo: 0000   # then this will be taken

---

您可以使用以下方法使其更加健壮：

with open("f.txt") as f, open("mod.txt","w") as writer:
    for line in f:
        if nxt in line.lower():
            writer.write(line)
            nxt = next(t)       # advance to the next thing to be read
        elif starter in line.lower():
            print("Incomplete set - beginning next one")
            while True:
                nxt = next(t)
                if nxt == starter:
                    break
                nxt = next(t)
                writer.write(line)

如果数据不完整，现在站在新的Name: ... 线上，这会重新开始，不会错过......