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.
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 new to working with python-chess and I was perusing the official documentation. I noticed this very weird thing I just can't make sense of. This is from the documentation:
import chess.pgn
pgn = open("data/pgn/kasparov-deep-blue-1997.pgn")
first_game = chess.pgn.read_game(pgn)
second_game = chess.pgn.read_game(pgn)
So as you can see the exact same function pgn.read_game() results in two different games to show up. I tried with my own pgn file and sure enough first_game == second_game resulted in False. I also tried third_game = chess.pgn.read_game() and sure enough that gave me the (presumably) third game from the pgn file. How is this possible? If I'm using the same function shouldn't it return the same result every time for the same file? Why should the variable name matter(I'm assuming it does) unless programming languages changed overnight or there's a random function built-in somewhere?
The only way that this can be possible is if some data is changing. This could be data that chess.pgn.read_game reads from elsewhere, or could be something to do with the object you're passing in.
In Python, file-like objects store where they are in the file. If they didn't, then this code:
with open("/home/wizzwizz4/Documents/TOPSECRET/diary.txt") as f:
line = f.readline()
while line:
print(line, end="")
line = f.readline()
would just print the first line over and over again. When data's read from a file, Python won't give you that data again unless you specifically ask for it.
There are multiple games in this file, stored one after each other. You're passing in the same file each time, but you're not resetting the read cursor to the beginning of the file (f.seek(0)) or closing and reopening the file, so it's going to read the next data available – i.e., the next game.
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.
I'm struggling to get my code to work on python it is meant to print the data in alphabetical order but doesn't can anyone help?
if choice.lower() == 'az':
dictionary={}
fi = open("class1.txt",'r')
data = fi.readlines()
for line in sorted(data):
print(data.rstrip());
You don't need to use readlines here, sorted is able to iterate over the file just fine. You should be printing line.strip() instead of data.strip()
with open("class1.txt",'r') as fi:
for line in sorted(fi):
print(line.rstrip())
I've also shown you how to use a context manager here (the with line). This causes the file to be closed automatically at the end of the block
You're applying rstrip wrong:
print(line.rstrip());
should do the trick.
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')