How can I get the last occurence of a text in a file that is automatically updated - python?

Question

[PROBLEM]

In a File that refreshes automatically with new data, I want to get: - the number that corresponds to latest string occcurence. For instance, in the dummy example below above I want to fetch: - last occurence of stringZ and afterwards the number inside that text. In practical terms I want to fetch: [99]

File sample:    
    "....
    Manually launch test 1 stringX
    Manually launch test 2 stringY
    Manually launch test 3 stringW
    Manually launch test 10 stringZ
    ................
    Manually launch test 200 stringX
    Manually launch test 300 stringY
    Manually launch test 77 stringW
    Manually launch test 99 stringZ
    "

[CODE]

tempFile = open(fileName, "r")
while True:
    fileContent = str(tempFile.readlines())
    print temp
    latestOccurence= re.search("(.*)stringZ",fileContent ).group(0)
    latestOccurence= re.search('([0-9])+',latestOccurence).group(0)
    print latestOccurence

Do you mean how do I get the latest line written to a file as it updates? Also how are you watching the file? — Padraic Cunningham, Dec 05 '15 at 16:15
@GingerPlusPlus, that could be it although looking at `str(tempFile.readlines())` anything is possible — Padraic Cunningham, Dec 05 '15 at 16:17
In the example above. I have : [Manually launch test 10 stringZ] and after some lines I have [Manually launch test 99 stringZ]. I want to get : a) latest occurence of the line where: stringZ is(in this case: Manually launch test 99 stringZ) + b) latest number from that line (in this case: 99) — george, Dec 05 '15 at 16:17
@Padraic. yes ; last line containing stringZ. and from that line I will fetch the number (in my case 99) — george, Dec 05 '15 at 16:18
@user3438538, this is very simple, loop over the lines keeping track of each time you find `stringZ` and the last line that has your substring will be the line you want — Padraic Cunningham, Dec 05 '15 at 16:18
@user3438538, are you using a while loop to look for changes in the file? — Padraic Cunningham, Dec 05 '15 at 16:20
But how do you check later if you open the file outside the loop? You should really use watchdog https://pypi.python.org/pypi/watchdog — Padraic Cunningham, Dec 05 '15 at 16:23
I think it is duplication of http://stackoverflow.com/questions/12523044/how-can-i-tail-a-log-file-in-python — Paweł Kordowski, Dec 05 '15 at 16:25

wildwilhelm · Accepted Answer · 2015-12-05T16:30:24.037

0

regex = re.compile(r'Manually launch test ([0-9]+) stringZ')
while True:
    latestOccurrence = None
    with open(fileName) as tempFile:
        for line in tempFile:
            if "stringZ" in line:
                match = regex.match(line)
                if match:
                    latestOccurrence = int(match.group(1))
    # do something with latestOccurrence here?
    time.sleep(1)

edited Dec 05 '15 at 16:30

answered Dec 05 '15 at 16:21

wildwilhelm

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I think it is not solving the problem that the file can be updated – Paweł Kordowski Dec 05 '15 at 16:23
@ wildwilhelm. thanks for suggestion, in the same time it fetches both occurences, namely: 10 and 99. I will keep investigating...... – george Dec 05 '15 at 16:37
@user3438538 the code will match all occurrences in the file, but by the time the file is closed (i.e., where the comment "do something ..." is), the variable `latestOccurrence` should contain the last value found. – wildwilhelm Dec 05 '15 at 16:43

How can I get the last occurence of a text in a file that is automatically updated - python?

1 Answers1