I am working in python tkinter and I am trying to write a code for writing some contents to a file and saving it. I have used filedialog to do so. I wish to write the contents in every next line. While there are so errors in running the code, even after writing "\n", it is not writing to the next line. The "\n" just adds a space after.
How to resolve this issue?
I have tried using the "\n" keyword in different ways possible. Yet, it is not writing to the next line. Instead it only adds a space after, just like   does.
Following is the relevant part of the code:
def save_file(event=""):
data = filedialog.asksaveasfile(mode="w", defaultextension=".html")
if data is None:
return
data.write("Content-1" + "\n"+ "Content-2" + "\n")
data.close()
I expect the data to be written in the file as:
Content-1
Content-2
But it is writing to the file as:
Content-1 Content-2
You are creating html - files. \n it it are meaningless if you look at your file using a browser (which is the go-to for html-files).
You need to write html-linebreaks to you file if you want it to break using a browser when displaying the interpreted html.
data.write("Content-1" + "<br>\n"+ "Content-2" + "<br>\n")
That way you can "see" htlm newlines in your browser.
Edit your file in a Textfile-editor -not a browser- to see the \n that are actually written to your file.
Related
def update(login_info):
stids = 001
file = open('regis.txt', 'r+')
for line in file:
if stids in line:
x = eval(line)
print(x)
c = input('what course you would like to update >> ')
get = x.get(c)
print('This is your current mark for the course', get)
mark = input('What is the new mark? >>')
g = mark.upper()
x.update({c: g})
file.write(str(x))
Before writing into the file
After writing into the file
This is what happens in the idle
As you can see, the system is not writing the data into the original dictionary. How can we improve on that? Pls, explain in detail. Thx all
Python doesn't just make relations like that. In Python's perspective, you are reading a regular text file, executing a command from the line read. That command creates an object which has no relationship to the line it was created from. But writing to the file should still work in my opinion. But you moved a line further (because you read the line where the data was and now you are at the end of it).
When you read a file, the position of where we are on the file changes. Iterating over the file like that (i.e for line in file:) invokes implicitly next() on the file. For efficiency reasons, positioning is disabled (file.tell() will not tell the current position). When you wrote to the file, for some reason you appended the text to the end, and if you test it it will no longer continue the loop even though it is still on the second line.
Reading and writing at the same time looks like an undefined behaviour.
Beginner Python: Reading and writing to the same file
I'm a very inexperienced Python coder so it's quite possible that I'm approaching this particular problem in completely the wrong way but I'd appreciate any suggestions/help.
I have a Python script that goes through a Markdown file line by line and rewrites [[wikilinks]] as standard Markdown [wikilink](wikilink) style links. I'm doing this using two regexes in one function as shown below:
def modify_links(file_obj):
"""
Function will parse file contents (opened in utf-8 mode) and modify standalone [[wikilinks]] and in-line
[[wikilinks]](wikilinks) into traditional Markdown link syntax.
:param file_obj: Path to file
:return: List object containing modified text. Newlines will be returned as '\n' strings.
"""
file = file_obj
linelist = []
logging.debug("Going to open file %s for processing now.", file)
try:
with open(file, encoding="utf8") as infile:
for line in infile:
linelist.append(re.sub(r"(\[\[)((?<=\[\[).*(?=\]\]))(\]\])(?!\()", r"[\2](\2.md)", line))
# Finds references that are in style [[foo]] only by excluding links in style [[foo]](bar).
# Capture group $2 returns just foo
linelist_final = [re.sub(r"(\[\[)((?<=\[\[)\d+(?=\]\]))(\]\])(\()((?!=\().*(?=\)))(\))",
r"[\2](\2 \5.md)", line) for line in linelist]
# Finds only references in style [[foo]](bar). Capture group $2 returns foo and capture group $5
# returns bar
except EnvironmentError:
logging.exception("Unable to open file %s for reading", file)
logging.debug("Finished processing file %s", file)
return linelist_final
This works fine for most Markdown files. However, I can occasionally get a Markdown file that has [[wikilinks]] within fenced code blocks such as the following:
# Reference
Here is a reference to “the Reactome Project” using smart quotes.
Here is an image: 
[[201802150808]](Product discovery)
```
[[201802150808 Product Prioritization]]
def foo():
print("bar")
```
In the above case I should skip processing the [[201802150808 Product Prioritization]] inside the fenced code block. I have a regex that identifies the fenced code block correctly namely:
(?<=```)(.*?)(?=```)
However, since the existing function is running line by line, I have not been able to figure out a way to skip the entire section in the for loop. How do I go about doing this?
You need to use a full Markdown parser to be able to cover all of the edge cases. Of course, most Markdown parsers convert Markdown directly to HTML. However, a few will use a two step process where step one converts the raw text to an Abstract Syntax Tree (AST) and step two renders the AST to the output format. It is not uncommon to find a Markdown renderer (outputs Markdown) which can replace the default HTML renderer.
You would simply need to modify either the parser step (using a plugin to add support for the wikilink syntax) or modify the AST directly. Then pass the AST to a Markdown renderer, which will give you a nicely formatted and normalized Markdown document. If you are looking for a Python solution, mistunePandoc Filters might be a good place to start.
But why go through all that when a few well crafted regular expressions can be run on the source text? Because Markdown parsing is complicated. I know, it seems easy at first. After all Markdown is easy to read for a human (which was one of its defining design goals). However, parsing is actually very complicated with parts of the parser reliant on previous steps.
For example, in addition to fenced code blocks, what about indented code blocks? But you can't just check for indentation at the beginning of a line, because a single line of a nested list could look identical to an indented code block. You want to skip the code block, but not the paragraph nested in a list. And what if your wikilink is broken across two lines? Generally when parsing inline markup, Markdown parsers will treat a single line break no different than a space. The point of all of this is that before you can start parsing inline elements, the entire document needs to first be parsed into its various block-level elements. Only then can you step through those and parse inline elements like links.
I'm sure there are other edge cases I haven't thought of. The only way to cover them all is to use a full-fledged Markdown parser.
I was able to create a reasonably complete solution to this problem by making a few changes to my original function, namely:
Replace the python re built-in with the regex module available on PyPi.
Change the function to read the entire file into a single variable instead of reading it line by line.
The revised function is as follows:
import regex
def modify_links(file_obj):
"""
Function will parse file contents (opened in utf-8 mode) and modify standalone [[wikilinks]] and in-line
[[wikilinks]](wikilinks) into traditional Markdown link syntax.
:param file_obj: Path to file
:return: String containing modified text. Newlines will be returned as '\\n' in the string.
"""
file = file_obj
try:
with open(file, encoding="utf8") as infile:
line = infile.read()
# Read the entire file as a single string
linelist = regex.sub(r"(?V1)"
r"(?s)```.*?```(*SKIP)(*FAIL)(?-s)|(?s)`.*?`(*SKIP)(*FAIL)(?-s)"
# Ignore fenced & inline code blocks. V1 engine allows in-line flags so
# we enable newline matching only here.
r"|(\ {4}|\t).*(*SKIP)(*FAIL)"
# Ignore code blocks beginning with 4 spaces/1 tab
r"|(\[\[(.*)\]\](?!\s\(|\())", r"[\3](\3.md)", line)
# Finds references that are in style [[foo]] only by excluding links in style [[foo]](bar) or
# [[foo]] (bar). Capture group $3 returns just foo
linelist_final = regex.sub(r"(?V1)"
r"(?s)```.*?```(*SKIP)(*FAIL)(?-s)|(?s)`.*?`(*SKIP)(*FAIL)(?-s)"
r"|(\ {4}|\t).*(*SKIP)(*FAIL)"
# Refer comments above for this portion.
r"|(\[\[(\d+)\]\](\s\(|\()(.*)(?=\))\))", r"[\3](\3 \5.md)", linelist)
# Finds only references in style [[123]](bar) or [[123]] (bar). Capture group $3 returns 123 and capture
# group $5 returns bar
except EnvironmentError:
logging.exception("Unable to open file %s for reading", file)
return linelist_final
The above function handles [[wikilinks]] in inline code blocks, fenced code blocks and code blocks indented with 4 spaces. There is currently one false positive scenario where it ignores a valid [[wiklink]] which is when the link appears on the 3rd level or deeper of a Markdown list, i.e.:
* Level 1
* Level 2
* [[wikilink]] #Not recognized
* [[wikilink]] #Not recognized.
However my documents do not have wikilinks nested at that level in lists so it's not a problem for me.
I have a simple program that manipulates some stored data on some text files. However I have to store the name and the password on different files for python to read.
I was wondering if I could get these two words (The name and the password) on two separate lines on one file and get python to overwrite just one of the lines based on what I choose to overwrite (either the password or the name).
I can get python to read specific lines with:
linenumber=linecache.getline("example.txt",4)
Ideally id like something like this:
linenumber=linecache.writeline("example.txt","Hello",4)
So this would just write "Hello" in "example.txt" only on line 4.
But unfortunately it doesn't seem to be as simple as that, I can get the words to be stored on separate files but overall doing this on a larger scale, I'm going to have a lot of text files all named differently and with different words on them.
If anyone would be able to help, it would be much appreciated!
Thanks, James.
You can try with built in open() function:
def overwrite(filename,newline,linenumber):
try:
with open(filename,'r') as reading:
lines = reading.readlines()
lines[linenumber]=newline+'\n'
with open(filename,'w') as writing:
for i in lines:
writing.write(i)
return 0
except:
return 1 #when reading/writing gone wrong, eg. no such a file
Be careful! It is writing all the lines all over again in a loop and when it comes to exception example.txt may already be blank. You may want to store all the lines in list all the time to write them back to file in exception. Or keep backup of your old files.
stackoverflow.
I've been trying to get the following code to create a .txt file, write some string on it and then print some message if said string was in the file. This is merely a study for a more complex project, but even given it's simplicity, it's still not working.
Code:
import io
file = open("C:\\Users\\...\\txt.txt", "w+") #"..." is the rest of the file destination
file.write('wololo')
if "wololo" in file.read():
print ("ok")
This function always skips the if as if there was no "wololo" inside the file, even though I've checked it all times and it was properly in there.
I'm not exactly sure what could be the problem, and I've spend a great deal of time searching everywhere for a solution, all to no avail. What could be wrong in this simple code?
Oh, and if I was to search for a string in a much bigger .txt file, would it still be wise to use file.read()?
Thanks!
When you write to your file, the cursor is moved to the end of your file. If you want to read the data aferwards, you'll have to move the cursor to the beginning of the file, such as:
file = open("txt.txt", "w+")
file.write('wololo')
file.seek(0)
if "wololo" in file.read():
print ("ok")
file.close() # Remember to close the file
If the file is big, you should consider to iterate over the file line by line instead. This would avoid that the entire file is stored in memory. Also consider using a context manager (the with keyword), so that you don't have to explicitly close the file yourself.
with open('bigdata.txt', 'rb') as ifile: # Use rb mode in Windows for reading
for line in ifile:
if 'wololo' in line:
print('OK')
else:
print('String not in file')
I'm new both to this site and python, so go easy on me. Using Python 3.3
I'm making a hangman-esque game, and all is working bar one aspect. I want to check whether a string is in a .txt file, and if not, write it on a new line at the end of the .txt file. Currently, I can write to the text file on a new line, but if the string already exists, it still writes to the text file, my code is below:
Note that my text file has each string on a seperate line
write = 1
if over == 1:
print("I Win")
wordlibrary = file('allwords.txt')
for line in wordlibrary:
if trial in line:
write = 0
if write == 1:
with open("allwords.txt", "a") as text_file:
text_file.write("\n")
text_file.write(trial)
Is this really the indentation from your program?
As written above, in the first iteration of the loop on wordlibrary,
the trial is compared to the line, and since (from your symptoms) it is not contained in the first line, the program moves on to the next part of the loop: since write==1, it will append trial to the text_file.
cheers,
Amnon
You dont need to know the number of lines present in the file beforehand. Just use a file iterator. You can find the documentation here : http://docs.python.org/2/library/stdtypes.html#bltin-file-objects
Pay special attention to the readlines method.