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read data from multiple files but would like to write that data into a new text file but file shows up blank

the code reads from multiple text files so far i have it to display on the terminal but i would like to have the info written into a text file but the text file shows up blank and dont know why new to python so still haven't figured out all the commands.
directory = 'C:\Assignments\\CPLfiles\*'
test = False
start_text = '^GMWE'
for filename in glob.glob(directory):
with open(filename) as f:
with open('file.txt', 'w') as f1:
for line in f:
#for x in line:
if test is False:
if re.search(start_text, line.strip()) is not None:
x = line.strip()
f1.write(x+ '\n')
print(x)
break
test = False

I think you should change the order of opening files to the following.
The problem is that for each file you open to read, you're also re-opening the file to write, whipping it's contents.
Also, due to the break you will write at maximum one line per file due to the break after the write statement.
If the last file that you opened does not have any match with the regular expression, then nothing will exist in the final file.
Hope it makes sense
directory = 'C:\Assignments\\CPLfiles\*'
test = False
start_text = '^GMWE'
with open('file.txt', 'w') as f1:
for filename in glob.glob(directory):
with open(filename) as f:
for line in f:
#for x in line:
if test is False:
if re.search(start_text, line.strip()) is not None:
x = line.strip()
f1.write(x+ '\n')
print(x)
break
test = False

I think that the main problem here is that you reopen file.txt for each file in you globbing. Each time opening it in write mode erases the file. If no line match in the last file you will end up with an empty file as a result. So your loop should be inside your with that opens this file.

Print an array, dict, list into a text file on Python

I'm trying to print a list or dict of file names into a text file. it's currently only returning the first item on the list. the items are fetched from s3 Aws.I'm using Python 2.6
for obj in bucket.objects.filter(Prefix=prefix):
s = obj.key
with open('test.txt', 'w') as f:
f.write(s)

The problem here is that for every item, you create a new file (in case the file already exists, you remove the content so to speak), and then write s to it.
So you should swap the order of things here:
with open('test.txt', 'w') as f: # first open the file
for obj in bucket.objects.filter(Prefix=prefix): # then iterate
f.write(obj.key)
So we keep the file handle open, and each item will be written. A potential problem is that you will not write a new line after you written the key of an object. We can do this by writing a new line as well:
with open('test.txt', 'w') as f:
for obj in bucket.objects.filter(Prefix=prefix):
f.write(obj.key)
f.write('\n')

whenever you open a file for writing, the previous content is erased and new text is written. So in this case you are erasing whatever you wrote to the file in the next iteration. you can do it in this way or open the file in "append" mode and continue with what you have written.
f= open("test.txt", "w")
for obj in bucket.objects.filter(Prefix=prefix):
s = obj.key
f.write(s)
f.write('\n)
f.close()

Appends text file instead of overwritting it

The context is the following one, I have two text file that I need to edit.
I open the first text file read it line by line and edit it but sometimes when I encounter a specific line in the first text file I need to overwritte content of the the second file.
However, each time I re-open the second text file instead of overwritting its content the below code appends it to the file...
Thanks in advance.
def edit_custom_class(custom_class_path, my_message):
with open(custom_class_path, "r+") as file:
file.seek(0)
for line in file:
if(some_condition):
file.write(mu_message)
def process_file(file_path):
with open(file_path, "r+") as file:
for line in file:
if(some_condition):
edit_custom_class(custom_class_path, my_message)

In my opinion, simultaneously reading and modifying a file is a bad thing to do. Consider using something like this. First read the file, make modifications, and then overwrite the file completely.
def modify(path):
out = []
f = open(path)
for line in f:
if some_condition:
out.append(edited_line) #make sure it has a \n at the end
else:
out.append(original_line)
f.close()
with open(path,'w') as f:
for line in out:
f.write(line)

How to write to .txt files in Python 3

I have a .txt file in the same folder as this .py file and it has this in it:
cat\n
dog\n
rat\n
cow\n
How can I save a var (var = 'ant') to the next line of the .txt file?

Open the file in append mode and write a new line (including a \n line separator):
with open(filename, 'a') as out:
out.write(var + '\n')
This adds the line at the end of the file after all the other contents.

Just to be complete on this question:
You can also use the print function.
with open(filename, 'a') as f:
print(var, file=f)
The print function will automatically end each print with a newline (unless given an alternative ending in the call, for example print(var, file=f, end='') for no newlines).

Slow python file I:O; Ruby runs better than this; Got the wrong language?

Please advise - I'm going to use this asa learning point. I'm a beginner.
I'm splitting a 25mb file into several smaller file.
A Kindly guru here gave me a Ruby sript. It works beautifully fast. So, in order to learn I mimicked it with a python script. This runs like a three-legged cat (slow). I wonder if anyone can tell me why?
My python script
##split a file into smaller files
###########################################
def splitlines (file) :
fileNo=0001
outFile=open("C:\\Users\\dunner7\\Desktop\\Textomics\\Media\\LexisNexus\\ele\\newdocs\%s.txt" % fileNo, 'a') ## open file to append
fh = open(file, "r") ## open the file for reading
mylines = fh.readlines() ### read in lines
for line in mylines: ## for each line
if re.search("Copyright ", line): # if the line is equal to the regex
outFile.close() ## close the file
fileNo +=1 #and add one to the filename, starting to read lines in again
else: # otherwise
outFile=open("C:\\Users\\dunner7\\Desktop\\Textomics\\Media\\LexisNexus\\ele\\newdocs\%s.txt" % fileNo, 'a') ## open file to append
outFile.write(line) ## then append it to the open outFile
fh.close()
The guru's Ruby 1.9 script
g=0001
f=File.open(g.to_s + ".txt","w")
open("corpus1.txt").each do |line|
if line[/\d+ of \d+ DOCUMENTS/]
f.close
f=File.open(g.to_s + ".txt","w")
g+=1
end
f.print line
end

There are many reasons why your script is slow -- the main reason being that you reopen the outputfile for almost every line you write. Since the old file gets implicitly closed on opening a new one (due to Python garbage collection), the write buffer is flushed for every single line you write, which is quite expensive.
A cleaned up and corrected version of your script would be
def file_generator():
file_no = 1
while True:
f = open(r"C:\Users\dunner7\Desktop\Textomics\Media"
r"\LexisNexus\ele\newdocs\%s.txt" % file_no, 'a')
yield f
f.close()
file_no += 1
def splitlines(filename):
files = file_generator()
out_file = next(files)
with open(filename) as in_file:
for line in in_file:
if "Copyright " in line:
out_file = next(files)
out_file.write(line)
out_file.close()

I guess the reason your script is so slow is that you open a new file descriptor for each line. If you look at your guru's ruby script, it closes and opens the output file only if your separator matches.
In contrast to that, your python script opens a new file descriptor for every line you read (and btw, does not close them). Opening a file requires talking to the kernel, so this is relatively slow.
Another change I would suggest is to change
fh = open(file, "r") ## open the file for reading
mylines = fh.readlines() ### read in lines
for line in mylines: ## for each line
to
fh = open(file, "r")
for line in fh:
With this change, you do not read the whole file into memory, but only block after block. Although it should not matter with a 25MiB file, it will hurt you with big files and is good practice (and less code ;)).

The Python code might be slow due to regex and not IO. Try
def splitlines (file) :
fileNo=0001
outFile=open("newdocs/%s.txt" % fileNo, 'a') ## open file to append
reg = re.compile("Copyright ")
for line in open(file, "r"):
if reg.search("Copyright ", line): # if the line is equal to the regex
outFile.close() ## close the file
outFile=open("newdocs%s.txt" % fileNo, 'a') ## open file to append
fileNo +=1 #and add one to the filename, starting to read lines in again
outFile.write(line) ## then append it to the open outFile
Several notes
Always use / instead of \ for path name
If regex is used repeatedly, compile it
Do you need re.search? or re.match?
UPDATE:
#Ed. S: point taken
#Winston Ewert: code updated to be closer to the original Ruby code

rosser,
Don't use names of built-in objects as identifiers in a code (file, splitlines)
The following code respects the effect of your own code: an out_file is closed without the line containing 'Copyright ' that constitutes the signal of closing
The use of the function writelines() is intended to obtain a faster execution than with a repetition of out_file.write(line)
The if li: block is there to trigger the closing of out_file in case the last line of the read file doesn't contains 'Copyright '
def splitfile(filename, wordstop, destrep, file_no = 1, li = []):
with open(filename) as in_file:
for line in in_file:
if wordstop in line:
with open(destrep+str(file_no)+'.txt','w') as f:
f.writelines(li)
file_no += 1
li = []
else:
li.append(line)
if li:
with open(destrep+str(file_no)+'.txt','w') as f:
f.writelines(li)