python parse conditional multiple lines in text file

Question

I would like to parse a text file, but with multiple conditions:

Input:

something<br />
something <br />
something<br />
Modifications made by xy (xy) on 2019/12/10 10:40:23<br />
location: A --> B<br />
something<br />
something<br />
something<br />
Modifications made by xz (xz) on 2020/01/17 11:11:59<br />
analyzer: C --> D<br />
analyzer: B --> D<br />
analyzer: G --> D<br />
location: E --> F<br />
something<br />
something<br />
something

Task: I need to find the "location: x --> y" and date before the location. The txt file can contains unknown number of location change.

Required Output:

2019/12/10 10:40:23, location: A --> B
2020/01/17 11:11:59, location: E --> F

I tried some code eg.:

with open('log.txt', 'r') as searchfile:
    for line in searchfile:
        if 'location' in line:
            print (line)

but only find the locations and I don't know how to find the dates for them.

Thank you in advance.

Sam Chats · Accepted Answer · 2020-02-03 20:23:21Z

2

Just keep track of corresponding times and locations as such:

with open('log.txt', 'r') as searchfile:
    time = None
    for line in searchfile:
        if line.startswith('Modifications made by'):
            time = line.split('on')[-1].strip()
        elif line.startswith('location') and time is not None:
            print(f'{time}, {line}')

edited Feb 3, 2020 at 20:23

answered Feb 3, 2020 at 14:36

Sam Chats

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1 Comment

Denes Over a year ago

Thank you @Sam. One modification. Instead of [1], [-1] showing the date but it works perfectly.

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