Python re.sub 不替换换行符

Question

I have some text like this:

<Row 1 Having A Text>
<Row 2 Having B Text>
<Row 3 Having C Text>

I am trying to remove entirely and shift up.

I have been trying to use this:

for line in fileinput.input(new_name, inplace=True): 
print (re.sub(r'<Row 2.*[\r\n]*', '', line.strip()))

However, this just results in the following:

<Row 1 Having A Text>

<Row 3 Having C Text>

And Row 3 does not move up. What am I missing here?

Answer 1

Your problem is that even though your regex matches and replaces the contents of line with an empty string ( '' ), print('') will output a blank line. Instead of printing every line, print just the lines that don't start with <Row 2

for line in fileinput.input(new_name, inplace=True): 
    if not line.strip().startswith('<Row 2'):
        print(line)

Answer 2

print() outputs the LF even if the content is empty, so you replace 'Row 2' with an empty string, but since you still use print , you get an empty line on output.

You may check for an empty line:

for line in fileinput.input(new_name, inplace=True): 
    output = re.sub(r'<Row 2.*[\r\n]*', '', line.strip())
    if len(output) :
        print(output)