I am writing a program for class that opens a file, counts the words, returns the number of words, and closes. I understand how to do everything excpet get the file to open and display the text This is what I have so far:
fname = open("C:\Python32\getty.txt")
file = open(fname, 'r')
data = file.read()
print(data)
The error I'm getting is:
TypeError: invalid file: <_io.TextIOWrapper name='C:\\Python32\\getty.txt' mode='r'
encoding='cp1252'>
The file is saved in the correct place and I have checked spelling, etc. I am using pycharm to work on this and the file that I am trying to open is in notepad.
You're using open() twice, so you've actually already opened the file, and then you attempt to open the already opened file object... change your code to:
fname = "C:\\Python32\\getty.txt"
infile = open(fname, 'r')
data = infile.read()
print(data)
The TypeError is saying that it cannot open type _io.TextIOWrapper which is what open() returns when opening a file.
Edit: You should really be handling files like so:
with open(r"C:\Python32\getty.txt", 'r') as infile:
data = infile.read()
print(data)
because when the with statement block is finished, it will handle file closing for you, which is very nice.
The r before the string will prevent python from interpreting it, leaving it exactly how you formed it.
Problem in the first line. Should be a simple assignment without the open. i.e. fname = "c:\Python32\getty.txt. Also, you'll be better off to escape the backslash (e.g. '\') or put an 'r' for the string literal (this isn't a problem with your specific program, buy may become a problem if you had a special character in your file name). Overall the program should be:
fname = r"c:\Python32\getty.txt"
file = open(fname,'r')
data = file.read()
print (data)
Put name part after file like:
data = file.name.read()
You are getting such errors because when you are writing directory of your file you are using a backslash \ and this is not good. You should use a forward slash /. E.g
file_ = open("C:/Python32/getty.txt", "r")
read = file_.read()
file_.close()
print read
From now on you got all file code under read.
file mode ('r', 'U', 'w', 'a', possibly with 'b' or '+' added)
Edit:
If you don't want to change the slashes then simply add an r before the string: r"path"
fname = r"C:\Python32\getty.txt"
file_ = open(fname, 'r')
data = file_.read()
print data
Related
I am new to programming and got an issue with writing bytes. Here is what I wrote:
file = open('filePath/input.train', 'wb')
for i in range(len(myList)):
file.write(bytes((myList[i]),'UTF-8'));
If I print 'i' here, it is 629.
The '.train' suffix is required by the project. In order to check it, I read it and write to a txt file:
file = open('filePath/input.train', 'rb')
content = file.read()
testFile = open('filePath/test.txt', 'wb')
testFile.write(content)
Now, the problem is, len(list) = 629 while I got 591 lines in test.txt file. It brought me problems later.
Why did this happen and how should I solve it?
first, when you open and write a file, need remember close the file after the write.like this.
file = open('filePath/input.train', 'wb')
for i in range(len(myList)):
file.write(bytes((myList[i]),'UTF-8'));
file.close()
second, python code not must has ";"
third, file is python's keyword, so don't use file be your variable name. you can use f or my_file or anyone, but don't use python's keyword.
fourth, python has a iterator, use iterator is better than your for i in range(len(xxx)).
all of this, your code can look like this.
f = open('filePath/input.train', 'wb')
for line in myList:
f.write(bytes(line, 'UTF-8'))
f.close()
I have a folder with csv formated documents with a .arw extension. Files are named as 1.arw, 2.arw, 3.arw ... etc.
I would like to write a code that reads all the files, checks and replaces the forwardslash / with a dash -. And finally creates new files with the replaced character.
The code I wrote as follows:
for i in range(1,6):
my_file=open("/path/"+str(i)+".arw", "r+")
str=my_file.read()
if "/" not in str:
print("There is no forwardslash")
else:
str_new = str.replace("/","-")
print(str_new)
f = open("/path/new"+str(i)+".arw", "w")
f.write(str_new)
my_file.close()
But I get an error saying:
'str' object is not callable.
How can I make it work for all the files in a folder? Apparently my for loop does not work.
The actual error is that you are replacing the built-in str with your own variable with the same name, then try to use the built-in str() after that.
Simply renaming the variable fixes the immediate problem, but you really want to refactor the code to avoid reading the entire file into memory.
import logging
import os
for i in range(1,6):
seen_slash = False
input_filename = "/path/"+str(i)+".arw"
output_filename = "/path/new"+str(i)+".arw"
with open(input_filename, "r+") as input, open(output_filename, "w") as output:
for line in input:
if not seen_slash and "/" in line:
seen_slash = True
line_new = line.replace("/","-")
print(line_new.rstrip('\n')) # don't duplicate newline
output.write(line_new)
if not seen_slash:
logging.warn("{0}: No slash found".format(input_filename))
os.unlink(output_filename)
Using logging instead of print for error messages helps because you keep standard output (the print output) separate from the diagnostics (the logging output). Notice also how the diagnostic message includes the name of the file we found the problem in.
Going back and deleting the output filename when you have examined the entire input file and not found any slashes is a mild wart, but should typically be more efficient.
This is how I would do it:
for i in range(1,6):
with open((str(i)+'.arw'), 'r') as f:
data = f.readlines()
for element in data:
element.replace('/', '-')
f.close()
with open((str(i)+'.arw'), 'w') as f:
for element in data:
f.write(element)
f.close()
this is assuming from your post that you know that you have 6 files
if you don't know how many files you have you can use the OS module to find the files in the directory.
I wrote the following python code snippet to append a lower p character to each line of a txt file:
f = open('helloworld.txt','r')
for line in f:
line+='p'
print(f.read())
f.close()
However, when I execute this python program, it returns nothing but an empty blank:
zhiwei#zhiwei-Lenovo-Rescuer-15ISK:~/Documents/1001/ass5$ python3 helloworld.py
Can anyone tell me what's wrong with my codes?
Currently, you are only reading each line and not writing to the file. reopen the file in write mode and write your full string to it, like so:
newf=""
with open('helloworld.txt','r') as f:
for line in f:
newf+=line.strip()+"p\n"
f.close()
with open('helloworld.txt','w') as f:
f.write(newf)
f.close()
well, type help(f) in shell, you can get "Character and line based layer over a BufferedIOBase object, buffer."
it's meaning：if you reading first buffer,you can get content, but again. it's empty。
so like this:
with open(oldfile, 'r') as f1, open(newfile, 'w') as f2:
newline = ''
for line in f1:
newline+=line.strip()+"p\n"
f2.write(newline)
open(filePath, openMode) takes two arguments, the first one is the path to your file, the second one is the mode it will be opened it. When you use 'r' as second argument, you are actually telling Python to open it as an only reading file.
If you want to write on it, you need to open it in writing mode, using 'w' as second argument. You can find more about how to read/write files in Python in its official documentation.
If you want to read and write at the same time, you have to open the file in both reading and writing modes. You can do this simply by using 'r+' mode.
It seems that your for loop has already read the file to the end, so f.read() return empty string.
If you just need to print the lines in the file, you could move the print into for loop just like print(line). And it is better to move the f.read() before for loop:
f = open("filename", "r")
lines = f.readlines()
for line in lines:
line += "p"
print(line)
f.close()
If you need to modify the file, you need to create another file obj and open it in mode of "w", and use f.write(line) to write the modified lines into the new file.
Besides, it is more better to use with clause in python instead of open(), it is more pythonic.
with open("filename", "r") as f:
lines = f.readlines()
for line in lines:
line += "p"
print(line)
When using with clause, you have no need to close file, this is more simple.
Started Python a week ago and I have some questions to ask about reading and writing to the same files. I've gone through some tutorials online but I am still confused about it. I can understand simple read and write files.
openFile = open("filepath", "r")
readFile = openFile.read()
print readFile
openFile = open("filepath", "a")
appendFile = openFile.write("\nTest 123")
openFile.close()
But, if I try the following I get a bunch of unknown text in the text file I am writing to. Can anyone explain why I am getting such errors and why I cannot use the same openFile object the way shown below.
# I get an error when I use the codes below:
openFile = open("filepath", "r+")
writeFile = openFile.write("Test abc")
readFile = openFile.read()
print readFile
openFile.close()
I will try to clarify my problems. In the example above, openFile is the object used to open file. I have no problems if I want write to it the first time. If I want to use the same openFile to read files or append something to it. It doesn't happen or an error is given. I have to declare the same/different open file object before I can perform another read/write action to the same file.
#I have no problems if I do this:
openFile = open("filepath", "r+")
writeFile = openFile.write("Test abc")
openFile2 = open("filepath", "r+")
readFile = openFile2.read()
print readFile
openFile.close()
I will be grateful if anyone can tell me what I did wrong here or is it just a Pythong thing. I am using Python 2.7. Thanks!
Updated Response:
This seems like a bug specific to Windows - http://bugs.python.org/issue1521491.
Quoting from the workaround explained at http://mail.python.org/pipermail/python-bugs-list/2005-August/029886.html
the effect of mixing reads with writes on a file open for update is
entirely undefined unless a file-positioning operation occurs between
them (for example, a seek()). I can't guess what
you expect to happen, but seems most likely that what you
intend could be obtained reliably by inserting
fp.seek(fp.tell())
between read() and your write().
My original response demonstrates how reading/writing on the same file opened for appending works. It is apparently not true if you are using Windows.
Original Response:
In 'r+' mode, using write method will write the string object to the file based on where the pointer is. In your case, it will append the string "Test abc" to the start of the file. See an example below:
>>> f=open("a","r+")
>>> f.read()
'Test abc\nfasdfafasdfa\nsdfgsd\n'
>>> f.write("foooooooooooooo")
>>> f.close()
>>> f=open("a","r+")
>>> f.read()
'Test abc\nfasdfafasdfa\nsdfgsd\nfoooooooooooooo'
The string "foooooooooooooo" got appended at the end of the file since the pointer was already at the end of the file.
Are you on a system that differentiates between binary and text files? You might want to use 'rb+' as a mode in that case.
Append 'b' to the mode to open the file in binary mode, on systems
that differentiate between binary and text files; on systems that
don’t have this distinction, adding the 'b' has no effect.
http://docs.python.org/2/library/functions.html#open
Every open file has an implicit pointer which indicates where data will be read and written. Normally this defaults to the start of the file, but if you use a mode of a (append) then it defaults to the end of the file. It's also worth noting that the w mode will truncate your file (i.e. delete all the contents) even if you add + to the mode.
Whenever you read or write N characters, the read/write pointer will move forward that amount within the file. I find it helps to think of this like an old cassette tape, if you remember those. So, if you executed the following code:
fd = open("testfile.txt", "w+")
fd.write("This is a test file.\n")
fd.close()
fd = open("testfile.txt", "r+")
print fd.read(4)
fd.write(" IS")
fd.close()
... It should end up printing This and then leaving the file content as This IS a test file.. This is because the initial read(4) returns the first 4 characters of the file, because the pointer is at the start of the file. It leaves the pointer at the space character just after This, so the following write(" IS") overwrites the next three characters with a space (the same as is already there) followed by IS, replacing the existing is.
You can use the seek() method of the file to jump to a specific point. After the example above, if you executed the following:
fd = open("testfile.txt", "r+")
fd.seek(10)
fd.write("TEST")
fd.close()
... Then you'll find that the file now contains This IS a TEST file..
All this applies on Unix systems, and you can test those examples to make sure. However, I've had problems mixing read() and write() on Windows systems. For example, when I execute that first example on my Windows machine then it correctly prints This, but when I check the file afterwards the write() has been completely ignored. However, the second example (using seek()) seems to work fine on Windows.
In summary, if you want to read/write from the middle of a file in Windows I'd suggest always using an explicit seek() instead of relying on the position of the read/write pointer. If you're doing only reads or only writes then it's pretty safe.
One final point - if you're specifying paths on Windows as literal strings, remember to escape your backslashes:
fd = open("C:\\Users\\johndoe\\Desktop\\testfile.txt", "r+")
Or you can use raw strings by putting an r at the start:
fd = open(r"C:\Users\johndoe\Desktop\testfile.txt", "r+")
Or the most portable option is to use os.path.join():
fd = open(os.path.join("C:\\", "Users", "johndoe", "Desktop", "testfile.txt"), "r+")
You can find more information about file IO in the official Python docs.
Reading and Writing happens where the current file pointer is and it advances with each read/write.
In your particular case, writing to the openFile, causes the file-pointer to point to the end of file. Trying to read from the end would result EOF.
You need to reset the file pointer, to point to the beginning of the file before through seek(0) before reading from it
You can read, modify and save to the same file in python but you have actually to replace the whole content in file, and to call before updating file content:
# set the pointer to the beginning of the file in order to rewrite the content
edit_file.seek(0)
I needed a function to go through all subdirectories of folder and edit content of the files based on some criteria, if it helps:
new_file_content = ""
for directories, subdirectories, files in os.walk(folder_path):
for file_name in files:
file_path = os.path.join(directories, file_name)
# open file for reading and writing
with io.open(file_path, "r+", encoding="utf-8") as edit_file:
for current_line in edit_file:
if condition in current_line:
# update current line
current_line = current_line.replace('john', 'jack')
new_file_content += current_line
# set the pointer to the beginning of the file in order to rewrite the content
edit_file.seek(0)
# delete actual file content
edit_file.truncate()
# rewrite updated file content
edit_file.write(new_file_content)
# empties new content in order to set for next iteration
new_file_content = ""
edit_file.close()
Started Python a week ago and I have some questions to ask about reading and writing to the same files. I've gone through some tutorials online but I am still confused about it. I can understand simple read and write files.
openFile = open("filepath", "r")
readFile = openFile.read()
print readFile
openFile = open("filepath", "a")
appendFile = openFile.write("\nTest 123")
openFile.close()
But, if I try the following I get a bunch of unknown text in the text file I am writing to. Can anyone explain why I am getting such errors and why I cannot use the same openFile object the way shown below.
# I get an error when I use the codes below:
openFile = open("filepath", "r+")
writeFile = openFile.write("Test abc")
readFile = openFile.read()
print readFile
openFile.close()
I will try to clarify my problems. In the example above, openFile is the object used to open file. I have no problems if I want write to it the first time. If I want to use the same openFile to read files or append something to it. It doesn't happen or an error is given. I have to declare the same/different open file object before I can perform another read/write action to the same file.
#I have no problems if I do this:
openFile = open("filepath", "r+")
writeFile = openFile.write("Test abc")
openFile2 = open("filepath", "r+")
readFile = openFile2.read()
print readFile
openFile.close()
I will be grateful if anyone can tell me what I did wrong here or is it just a Pythong thing. I am using Python 2.7. Thanks!
Updated Response:
This seems like a bug specific to Windows - http://bugs.python.org/issue1521491.
Quoting from the workaround explained at http://mail.python.org/pipermail/python-bugs-list/2005-August/029886.html
the effect of mixing reads with writes on a file open for update is
entirely undefined unless a file-positioning operation occurs between
them (for example, a seek()). I can't guess what
you expect to happen, but seems most likely that what you
intend could be obtained reliably by inserting
fp.seek(fp.tell())
between read() and your write().
My original response demonstrates how reading/writing on the same file opened for appending works. It is apparently not true if you are using Windows.
Original Response:
In 'r+' mode, using write method will write the string object to the file based on where the pointer is. In your case, it will append the string "Test abc" to the start of the file. See an example below:
>>> f=open("a","r+")
>>> f.read()
'Test abc\nfasdfafasdfa\nsdfgsd\n'
>>> f.write("foooooooooooooo")
>>> f.close()
>>> f=open("a","r+")
>>> f.read()
'Test abc\nfasdfafasdfa\nsdfgsd\nfoooooooooooooo'
The string "foooooooooooooo" got appended at the end of the file since the pointer was already at the end of the file.
Are you on a system that differentiates between binary and text files? You might want to use 'rb+' as a mode in that case.
Append 'b' to the mode to open the file in binary mode, on systems
that differentiate between binary and text files; on systems that
don’t have this distinction, adding the 'b' has no effect.
http://docs.python.org/2/library/functions.html#open
Every open file has an implicit pointer which indicates where data will be read and written. Normally this defaults to the start of the file, but if you use a mode of a (append) then it defaults to the end of the file. It's also worth noting that the w mode will truncate your file (i.e. delete all the contents) even if you add + to the mode.
Whenever you read or write N characters, the read/write pointer will move forward that amount within the file. I find it helps to think of this like an old cassette tape, if you remember those. So, if you executed the following code:
fd = open("testfile.txt", "w+")
fd.write("This is a test file.\n")
fd.close()
fd = open("testfile.txt", "r+")
print fd.read(4)
fd.write(" IS")
fd.close()
... It should end up printing This and then leaving the file content as This IS a test file.. This is because the initial read(4) returns the first 4 characters of the file, because the pointer is at the start of the file. It leaves the pointer at the space character just after This, so the following write(" IS") overwrites the next three characters with a space (the same as is already there) followed by IS, replacing the existing is.
You can use the seek() method of the file to jump to a specific point. After the example above, if you executed the following:
fd = open("testfile.txt", "r+")
fd.seek(10)
fd.write("TEST")
fd.close()
... Then you'll find that the file now contains This IS a TEST file..
All this applies on Unix systems, and you can test those examples to make sure. However, I've had problems mixing read() and write() on Windows systems. For example, when I execute that first example on my Windows machine then it correctly prints This, but when I check the file afterwards the write() has been completely ignored. However, the second example (using seek()) seems to work fine on Windows.
In summary, if you want to read/write from the middle of a file in Windows I'd suggest always using an explicit seek() instead of relying on the position of the read/write pointer. If you're doing only reads or only writes then it's pretty safe.
One final point - if you're specifying paths on Windows as literal strings, remember to escape your backslashes:
fd = open("C:\\Users\\johndoe\\Desktop\\testfile.txt", "r+")
Or you can use raw strings by putting an r at the start:
fd = open(r"C:\Users\johndoe\Desktop\testfile.txt", "r+")
Or the most portable option is to use os.path.join():
fd = open(os.path.join("C:\\", "Users", "johndoe", "Desktop", "testfile.txt"), "r+")
You can find more information about file IO in the official Python docs.
Reading and Writing happens where the current file pointer is and it advances with each read/write.
In your particular case, writing to the openFile, causes the file-pointer to point to the end of file. Trying to read from the end would result EOF.
You need to reset the file pointer, to point to the beginning of the file before through seek(0) before reading from it
You can read, modify and save to the same file in python but you have actually to replace the whole content in file, and to call before updating file content:
# set the pointer to the beginning of the file in order to rewrite the content
edit_file.seek(0)
I needed a function to go through all subdirectories of folder and edit content of the files based on some criteria, if it helps:
new_file_content = ""
for directories, subdirectories, files in os.walk(folder_path):
for file_name in files:
file_path = os.path.join(directories, file_name)
# open file for reading and writing
with io.open(file_path, "r+", encoding="utf-8") as edit_file:
for current_line in edit_file:
if condition in current_line:
# update current line
current_line = current_line.replace('john', 'jack')
new_file_content += current_line
# set the pointer to the beginning of the file in order to rewrite the content
edit_file.seek(0)
# delete actual file content
edit_file.truncate()
# rewrite updated file content
edit_file.write(new_file_content)
# empties new content in order to set for next iteration
new_file_content = ""
edit_file.close()