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Python script not finding value in log file when the value is in the file

The code below is meant to find any xls or csv file used in a process. The .log file contains full paths with extensions and definitely contains multiple values with "xls" or "csv". However, Python can't find anything...Any idea? The weird thing is when I copy the content of the log file and paste it to another notepad file and save it as log, it works then...
infile=r"C:\Users\me\Desktop\test.log"
important=[]
keep_words=["xls","csv"]
with open(infile,'r') as f:
for line in f:
for word in keep_words:
if word in line:
important.append(line)
print(important)

I was able to figure it out...encoding issue...
with io.open(infile,encoding='utf16') as f:

You must change the line
for line in f:
to
for line in f.readlines():
You made the python search in the bytes opened file, not in his content, even in his lines (in a list, just like the readlines method);
I hope I was able to help (sorry about my bad English).

File handling techniques in Python

How do I read a file by opening that particular file instead of printing it on the console? I've used the following code but it prints the contents of the file on the console.
fw=open("x.txt",'r+')
#fw.write("Hello\n")
#fw.write("Python is crazy af")
n=fw.read()
print(n)
fw.close()

The builtin open function makes the contents of a file available, meaning you can manipulate it with your code. If you don't want to print a line of it, you can do .readlines(). If you don't want to print it you can do anything else you want with it like store it in a variable.
One last note about file context:
with open("filename.txt", "r") as file:
for line in file:
# Do something with line here
This pattern is guaranteed to close, instead of calling open and close separately.
But if you wanted to open a text editor...
https://stackoverflow.com/a/6178200/10553976

How do I read a file by opening that particular file
The first 2 (non comment) lines of your answer do this:
fw=open("x.txt",'r+')
n=fw.read()
You have now read the contents of x.txt into the variable n
instead of printing it on the console?
Don't print it then. Remove the line
print(n)
and the contents of the file won't be printed.

What is the difference between opening and reading a file in python?

In python's OS module there is a method to open a file and a method to read a file.
The docs for the open method say:
Open the file file and set various flags according to flags and
possibly its mode according to mode. The default mode is 0777 (octal),
and the current umask value is first masked out. Return the file
descriptor for the newly opened file.
The docs for the read method say;
Read at most n bytes from file descriptor fd. Return a string
containing the bytes read. If the end of the file referred to by fd
has been reached, an empty string is returned.
I understand what it means to read n bytes from a file. But how does this differ from open?

"Opening" a file doesn't actually bring any of the data from the file into your program. It just prepares the file for reading (or writing), so when your program is ready to read the contents of the file it can do so right away.

Opening a file allows you to read or write to it (depending on the flag you pass as the second argument), whereas reading it actually pulls the data from a file that is typcially saved into a variable for processing or printed as output.
You do not always read from a file once it is opened. Opening also allows you to write to a file, either by overwriting all the contents or appending to the contents.
To read from a file:
>>> myfile = open('foo.txt', 'r')
>>> myfile.read()
First you open the file with read permission (r)
Then you read() from the file
To write to a file:
>>> myfile = open('foo.txt', 'r')
>>> myfile.write('I am writing to foo.txt')
The only thing that is being done in line 1 of each of these examples is opening the file. It is not until we actually read() from the file that anything is changed

open gets you a fd (file descriptor), you can read from that fd later.
One may also open a file for other purpose, say write to a file.

It seems to me you can read lines from the file handle without invoking the read method but I guess read() truly puts the data in the variable location. In my course we seem to be printing lines, counting lines, and adding numbers from lines without using read().
The rstrip() method needs to be used, however, because printing the line from the file handle using a for in statement also prints the invisible line break symbol at the end of the line, as does the print statement.
From Python for Everybody by Charles Severance, this is the starter code.
"""
7.2
Write a program that prompts for a file name,
then opens that file and reads through the file,
looking for lines of the form:
X-DSPAM-Confidence: 0.8475
Count these lines and extract the floating point
values from each of the lines and compute the
average of those values and produce an output as
shown below. Do not use the sum() function or a
variable named sum in your solution.
You can download the sample data at
http://www.py4e.com/code3/mbox-short.txt when you
are testing below enter mbox-short.txt as the file name.
"""
# Use the file name mbox-short.txt as the file name
fname = input("Enter file name: ")
fh = open(fname)
for line in fh:
if not line.startswith("X-DSPAM-Confidence:") :
continue
print(line)
print("Done")

Deleting the first line of a text file in python [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Editing specific line in text file in python
I am writing a software that allows users to write data into a text file. However, I am not sure how to delete the first line of the text file and rewrite the line. I want the user to be able to update the text file's first line by clicking on a button and inputing in something but that requires deleting and writing a new line as the first line which I am not sure how to implement. Any help would be appreciated.
Edit:
So I sought out the first line of the file and tried to write another line but that doesn't delete the previous line.
file.seek(0)
file.write("This is the new first line \n")

You did not describe how you opened the file to begin with. If you used file = open(somename, "a") that file will not be truncated but new data is written at the end (even after a seek on most if not all modern systems). You would have to open the file with "r+")
But your example assumes that the line you write is exactly the same length as what the user typed. There is no line organisation in the files, just bytes, some of which indicate line ending.
Wat you need to do is use a temporary file or a temporary buffer in memory for all the lines and then write the lines out with the first replaced.
If things fit in memory (which I assume since few users are going to type so much it does not fit), you should be able to do:
lines = open(somename, 'r').readlines()
lines[0] = "This is the new first line \n"
file = open(somename, 'w')
for line in lines:
file.write(line)
file.close()

You could use readlines to get an array of lines and then use del on the first index of the array. This might help. http://www.daniweb.com/software-development/python/threads/68765/how-to-remove-a-number-of-lines-from-a-text-file-

question about splitting a large file

Hey I need to split a large file in python into smaller files that contain only specific lines. How do I do this?

You're probably going to want to do something like this:
big_file = open('big_file', 'r')
small_file1 = open('small_file1', 'w')
small_file2 = open('small_file2', 'w')
for line in big_file:
if 'Charlie' in line: small_file1.write(line)
if 'Mark' in line: small_file2.write(line)
big_file.close()
small_file1.close()
small_file2.close()
Opening a file for reading returns an object that allows you to iterate over the lines. You can then check each line (which is just a string of whatever that line contains) for whatever condition you want, then write it to the appropriate file that you opened for writing. It is worth noting that when you open a file with 'w' it will overwrite anything already written to that file. If you want to simply add to the end, you should open it with 'a', to append.
Additionally, if you expect there to be some possibility of error in your reading/writing code, and want to make sure the files are closed, you can use:
with open('big_file', 'r') as big_file:
<do stuff prone to error>

Do you mean breaking it down into subsections? Like if I had a file with chapter 1, chapter 2, and chapter 3, you want it to be broken down into separate files for each chapter?
The way I've done this is similar to Wilduck's response, but closes the input file as soon as it reads in the data and keeps all the lines read in.
data_file = open('large_file_name', 'r')
lines = data_file.readlines()
data_file.close()
outputFile = open('output_file_one', 'w')
for line in lines:
if 'SomeName' in line:
outputFile.write(line)
outputFile.close()
If you wanted to have more than one output file you could either add more loops or open more than one outputFile at a time.
I'd recommend using Wilducks response, however, as it uses less space and will take less time with larger files since the file is read only once.

How big and does it need to be done in python? If this is on unix, would split/csplit/grep suffice?

First, open the big file for reading.
Second, open all the smaller file names for writing.
Third, iterate through every line. Every iteration, check to see what kind of line it is, then write it to that file.
More info on File I/O: http://docs.python.org/tutorial/inputoutput.html