Im really get confused.
Im solving PySchool Practices for university and get a problem at Topic 13: Question 2.
I need to:
Create a function that appends the name and email to the end of a named file.
Code i use:
# Create a function that appends the name and email to the end of a named file.
def addEmail(filename, name, email):
f = open(filename, 'a') # replace the mode
f.write("\n"+name+' '+email)
# Append name and email, each record should end with '\n'.
f.close()
# close file
return f # do not remove this line
I get:
Error
I cant understand where is my mistake.Please help.
Your code puts a newline character at the beginning of the line added to the file. However, it's very likely that the file already has a newline character at the end of the last line to begin with.
Rather you should put you newline character at the end of the line you add. I've tried this variation; it works.
can you check if the file is in the same directory or if it is the full file location. Also I suggest you to use with:
#with will close file automatically when code is done
with open(filename, 'a') as f:
# If using python 3.6 and up you can use f-String formatting
f.write(f'\n{name} {email}')
Related
I'm trying to create a webscraping script in Python where I follow a bunch of links and insert them into a .txt file. However, I want to do this only if the website already doesn't exist in the file.
I have written this code to insert the given website link into the file, so far (not working):
def writeSite(site):
file = open("websites.txt", 'a+')
# print(site)
if site in file.read():
return
file.write(site + "\n")
file.close()
Thanks in advance.
You were pretty close, but because you open the file to append to it, it starts with the file pointer at the end. You need to seek to the start to read its contents again:
def writeSite(site):
file = open("websites.txt", 'a+')
file.seek(0)
# print(site)
if site in file.read():
return
file.write(site + "\n")
file.close()
However, keep in mind that site in file.read() is very crude.
For example, imagine you already have 'http://somesite.com/page/' in the file but now you want to add 'http://somesite.com/' - the URL as a whole is not in the file, but your test will find it.
If you want to check whole lines (and be sure you deal with the file nicely), this would be better:
def writeSite(site):
site += '\n'
with open("websites.txt", 'a+') as f:
f.seek(0)
if site in f.readlines():
return
f.write(site)
It adds a newline to the name of the site to separate the URLs in the file and uses readlines to make use of that fact to check for the whole URL. Using with ensures the file always gets closed.
And since you want to read before writing anyway, you could use 'r+' as a mode, and skip the seek - but only if you can be sure the file already exists. I assume you chose 'a+' because that isn't the case.
(in case you worry that this changes the value of site - that's only true for the parameter inside the function. Whatever value you passed in outside the function will remain unaffected)
I am trying to make a program that reads from a file and deletes one specific line inside of it and then puts all the data stored back to the file separated with a new line. The file uses this format:
Jones|20|20|00
bob|30|19|90
James|40|19|80
So I want to delete (backup contains this and is the line I want to delete)
bob|30|19|90
but the code that I am using takes away the new line and doesnt replace it but when I try to add \n to it the file doesn't want to read as it does this (adds 2 "\n"s):
Jones|20|20|00
James|40|19|80
I am using this code below:
def deleteccsaver(backup):
lockaccount =""
lockaccount = lockaccount.strip("\n")
with open('accounts_project.txt','r+') as f:
newline=[]
for line in f.readlines():
newline.append(line.replace(backup, lockaccount).strip("\n"))
with open('accounts_project.txt','w+') as f:
for line in newline:
f.writelines(line +"\n")
f.close()
resetlogin()
Please help as I dont know how to add the \n back without it appearing as "\n\n"
Without the "\n "it appears as:
Jones|20|20|00James|40|19|80
Any suggestions:
What I am doing here is reading the entire file at once, please don't do this if you have a very very big file. After reading all file contents at once, I am making a list out of it using "\n" as a delimiter. Read about split function in python to know more about it. Then from the list I am replacing the backup with lockaccount, as you have been doing the same, these are the names of variables that you are using, hope I did not confuse between them in this case. Then it will be saved to a new file after adding new line after each element of list, i.e. each line of the previous file. This will cause the result file to have all the contents as previous file, but removing what you wanted to remove. I see that lockaccount is itself an empty string, so adding it might create a newline in your file. In case you dont want lockaccount to replace the backup variable in the file, just remove the backup from the list using contents.remove(backup) instead of contents[contents.index(backup)] == lockaccount keeping the rest of the code same. Hope this explains better.
def deleteccsaver(backup):
lockaccount =""
lockaccount = lockaccount.strip("\n")
with open('accounts_project.txt','r+') as f:
contents = f.read().split("\n")
if backup in contents:
contents[contents.index(backup)] = lockaccount
new_contents = "\n".join(contents)
with open('accounts_project.txt','w+') as f:
f.write(new_contents)
resetlogin()
You are priting a newline character after each element in the list. So, if you replace a line with the empty string, well, you will get an empty line.
Try to simply skip over the line you want to delete:
if line == backup:
contiune
else:
lines.append(...)
PS. There is room for improvment in the code above, but I'm on the phone, I will get back with an edit later if nobody gets ahead of me
You can try to add newline = '\n'.join(newline) after your first for loop and then just write it into the accounts_project.txt file without a loop.
The code should then look like:
def deleteccsaver(backup):
lockaccount =""
lockaccount = lockaccount.strip("\n")
with open('accounts_project.txt','r+') as f:
newline=[]
for line in f.readlines():
newline.append(line.replace(backup, lockaccount).strip("\n"))
newline = '\n'.join(newline)
with open('accounts_project.txt','w+') as f:
f.write(newline)
f.close() # you don't necessarily need it inside a with statement
resetlogin()
Edit:
Above code still results in
Jones|20|20|00
James|40|19|80
as output.
That's because during the replacement loop an empty string will be appended to newline (like newline: ['Jones|20|20|00','','James|40|19|80']) and newline = '\n'.join(newline) will then result in 'Jones|20|20|00\n\nJames|40|19|80'.
A possible fix can be to replace:
for line in f.readlines():
newline.append(line.replace(backup, lockaccount).strip("\n"))
with
for line in f.readlines():
line = line.strip('\n')
if line != backup:
newline.append(line)
def deleteccsaver(backup):
lockaccount =""
lockaccount = lockaccount.strip("\n")
with open('accounts_project.txt','r+') as f:
contents = f.read().split("\n")
if backup in contents:
contents.remove(backup)
new_contents = "\n".join(contents)
with open('accounts_project.txt','w+') as f:
f.write(new_contents)
resetlogin()
I'm working on a project at the end of a book I read for Python, so in case this hasn't given it away for you, I'm still quite new to this.
I'm trying to use the open command to open a file that I know exists. I know that the code understands the file is there, because when I switch over to write mode, it clears my text file out, telling me that it can find the file but it just won't read it. Why is this happening? Here's the code-
openFile = open('C:\\Coding\\Projects\\Python\\One Day Project\\BODMAS\\userScores.txt', 'r')
def getUserPoint(userName):
for line in openFile:
split(',')
print(line, end = "")
I've tried a few variations where my openFile function is a local variable inside getUserPoint(), but that didn't make a difference either.
Editing because I missed a vital detail — the userScores.txt file is laid out as follows:
Annie, 125
The split() function is supposed to split the name and the score assigned to the name.
Your function isn't valid Python, as split isn't a globally defined function, but a built-in function of the type str. Try changing your function to something like this.
def getUserPoint(name):
for line in openFile:
line_split = line.split(",")
print(line_split, end = "")
I'm trying to store a file I create on an ftp server.
I've been able to create the temp file and store it as an empty file, but I haven't been able to write any data to the file before storing it.
Here is the partially working code:
#Loggin to server.
ftp = FTP(Integrate.ftp_site)
ftp.login(paths[0], paths[1])
ftp.cwd(paths[3])
f = tempfile.SpooledTemporaryFile()
# Throws error.
f.write(bytes("hello", 'UTF-8'))
#No error, doesn't work.
#f.write("hello")
#Also, doesn't throw error, and doesn't write anything to the file.
# f.write("hello".encode('UTF-8'))
file_name = "test.txt"
ftp.storlines("Stor " + file_name, f)
#Done.
f.close()
ftp.quit()
What am I doing wrong?
Thanks
Seeking!
To know where to read or write in the file (or file-like object), Python keeps a pointer to a location in the file. The documentation simply calls it "the file's current position". So, if you have a filed with these lines in it:
hello world
how are you
You can read it with Python like in the following code. Note that the tell() function tells you the file's position.
>>> f = open('file.txt', 'r')
>>> f.tell()
0
>>> f.readline()
'hello world\n'
>>> f.tell()
12
Python is now twelve characters "into" the file. If you'd count the characters, that means it's right after the newline character (\n is a single character). Continuing to read from the file with readlines() or any other reading function will use this position to know where to start reading.
Writing to the file will also use and increment the position. This means that if, after writing to the file you read from the file, Python will start reading at the position it has saved (which is right after whatever you just wrote), not the beginning of the file.
The ftp.storlines() function uses the same readlines() function, which only starts reading at the file's position, so after whatever you wrote. You can solve this by seeking back to the start of the file before calling ftp.storlines(). Use f.seek(0) to reset the file position to the very start of the file.
The Problem - Update:
I could get the script to print out but had a hard time trying to figure out a way to put the stdout into a file instead of on a screen. the below script worked on printing results to the screen. I posted the solution right after this code, scroll to the [ solution ] at the bottom.
First post:
I'm using Python 2.7.3. I am trying to extract the last words of a text file after the colon (:) and write them into another txt file. So far I am able to print the results on the screen and it works perfectly, but when I try to write the results to a new file it gives me str has no attribute write/writeline. Here it the code snippet:
# the txt file I'm trying to extract last words from and write strings into a file
#Hello:there:buddy
#How:areyou:doing
#I:amFine:thanks
#thats:good:I:guess
x = raw_input("Enter the full path + file name + file extension you wish to use: ")
def ripple(x):
with open(x) as file:
for line in file:
for word in line.split():
if ':' in word:
try:
print word.split(':')[-1]
except (IndexError):
pass
ripple(x)
The code above works perfectly when printing to the screen. However I have spent hours reading Python's documentation and can't seem to find a way to have the results written to a file. I know how to open a file and write to it with writeline, readline, etc, but it doesn't seem to work with strings.
Any suggestions on how to achieve this?
PS: I didn't add the code that caused the write error, because I figured this would be easier to look at.
End of First Post
The Solution - Update:
Managed to get python to extract and save it into another file with the code below.
The Code:
inputFile = open ('c:/folder/Thefile.txt', 'r')
outputFile = open ('c:/folder/ExtractedFile.txt', 'w')
tempStore = outputFile
for line in inputFile:
for word in line.split():
if ':' in word:
splitting = word.split(':')[-1]
tempStore.writelines(splitting +'\n')
print splitting
inputFile.close()
outputFile.close()
Update:
checkout droogans code over mine, it was more efficient.
Try this:
with open('workfile', 'w') as f:
f.write(word.split(':')[-1] + '\n')
If you really want to use the print method, you can:
from __future__ import print_function
print("hi there", file=f)
according to Correct way to write line to file in Python. You should add the __future__ import if you are using python 2, if you are using python 3 it's already there.
I think your question is good, and when you're done, you should head over to code review and get your code looked at for other things I've noticed:
# the txt file I'm trying to extract last words from and write strings into a file
#Hello:there:buddy
#How:areyou:doing
#I:amFine:thanks
#thats:good:I:guess
First off, thanks for putting example file contents at the top of your question.
x = raw_input("Enter the full path + file name + file extension you wish to use: ")
I don't think this part is neccessary. You can just create a better parameter for ripple than x. I think file_loc is a pretty standard one.
def ripple(x):
with open(x) as file:
With open, you are able to mark the operation happening to the file. I also like to name my file object according to its job. In other words, with open(file_loc, 'r') as r: reminds me that r.foo is going to be my file that is being read from.
for line in file:
for word in line.split():
if ':' in word:
First off, your for word in line.split() statement does nothing but put the "Hello:there:buddy" string into a list: ["Hello:there:buddy"]. A better idea would be to pass split an argument, which does more or less what you're trying to do here. For example, "Hello:there:buddy".split(":") would output ['Hello', 'there', 'buddy'], making your search for colons an accomplished task.
try:
print word.split(':')[-1]
except (IndexError):
pass
Another advantage is that you won't need to check for an IndexError, since you'll have, at least, an empty string, which when split, comes back as an empty string. In other words, it'll write nothing for that line.
ripple(x)
For ripple(x), you would instead call ripple('/home/user/sometext.txt').
So, try looking over this, and explore code review. There's a guy named Winston who does really awesome work with Python and self-described newbies. I always pick up new tricks from that guy.
Here is my take on it, re-written out:
import os #for renaming the output file
def ripple(file_loc='/typical/location/while/developing.txt'):
outfile = "output.".join(os.path.basename(file_loc).split('.'))
with open(outfile, 'w') as w:
lines = open(file_loc, 'r').readlines() #everything is one giant list
w.write('\n'.join([line.split(':')[-1] for line in lines]))
ripple()
Try breaking this down, line by line, and changing things around. It's pretty condensed, but once you pick up comprehensions and using lists, it'll be more natural to read code this way.
You are trying to call .write() on a string object.
You either got your arguments mixed up (you'll need to call fileobject.write(yourdata), not yourdata.write(fileobject)) or you accidentally re-used the same variable for both your open destination file object and storing a string.