Read text file as string python

How to open file as formatted string?

You can do something like file.read().format(myvar=’myself’) , or if you prefer to have all the replacements in a dict like replacements = <'myvar': 'myself'>and then file.read().format(**replacements) . If you want to use variable names, then file.read().format(**locals()) or file.read().format(**globals()) .

@jdehesa could you please explain further how the .format(**locals()) or **globals() would work? I would still need to use a dictionary such as replacements that you showed right?

@Sosi No, locals() and globals() return a dictionary themselves, so unpacking them with ** will directly make them work as keyword-based replacements.

@Sosi I’m gonna star this and try to come back with a good answer this evening if someone hasn’t made one by then

2 Answers 2

This seems to work if the variable is local to the call, if it’s a global variable, use **globals() . You can also put the value in a dictionary that has the variable name as the key.

myvar = 'myself' newline = '\n' # Avoids SyntaxError: f-string expr cannot include a backslash with open('unformatted.txt', 'r') as file: myfile = f"".format(**locals()) print(myfile) 

Before seeing this answer, I spent 30 mins trying to understand why a working example was fine (such as the one you give), but when I had it in a function it wasn’t working. Now I see why 🙂

Assume there is «This is .» in file.txt.

with open('path/to/file.txt', 'r') as file: myfile = file.read().replace('\n', '') myvar='myself' print(myfile.format(myvar=myvar)) 

Any strings in plain text format, can be imported as a variable from a text file. Then the strings variable can be manipulated as normal.

In you case, the key is «». So you can easily use «.format(var=varx) as long as you defined variable «varx».

And if you want to import html template with css style and replace some contents, you can just use «>» to escape «».

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Python Read Text File

Summary: in this tutorial, you learn various ways to read text files in Python.

TL;DR

The following shows how to read all texts from the readme.txt file into a string:

with open('readme.txt') as f: lines = f.readlines()Code language: Python (python)

Steps for reading a text file in Python

To read a text file in Python, you follow these steps:

• First, open a text file for reading by using the open() function.
• Second, read text from the text file using the file read() , readline() , or readlines() method of the file object.
• Third, close the file using the file close() method.

1) open() function

The open() function has many parameters but you’ll be focusing on the first two:

open(path_to_file, mode)Code language: Python (python)

The path_to_file parameter specifies the path to the text file.

If the program and file are in the same folder, you need to specify only the filename of the file. Otherwise, you need to include the path to the file as well as the filename.

To specify the path to the file, you use the forward-slash ( ‘/’ ) even if you’re working on Windows.

For example, if the file readme.txt is stored in the sample folder as the program, you need to specify the path to the file as c:/sample/readme.txt

The mode is an optional parameter. It’s a string that specifies the mode in which you want to open the file. The following table shows available modes for opening a text file:

Mode	Description
‘r’	Open for text file for reading text
‘w’	Open a text file for writing text
‘a’	Open a text file for appending text

For example, to open a file whose name is the-zen-of-python.txt stored in the same folder as the program, you use the following code:

 f = open('the-zen-of-python.txt','r')Code language: Python (python)

The open() function returns a file object which you will use to read text from a text file.

2) Reading text methods

The file object provides you with three methods for reading text from a text file:

• read(size) – read some contents of a file based on the optional size and return the contents as a string. If you omit the size, the read() method reads from where it left off till the end of the file. If the end of a file has been reached, the read() method returns an empty string.
• readline() – read a single line from a text file and return the line as a string. If the end of a file has been reached, the readline() returns an empty string.
• readlines() – read all the lines of the text file into a list of strings. This method is useful if you have a small file and you want to manipulate the whole text of that file.

3) close() method

The file that you open will remain open until you close it using the close() method.

It’s important to close the file that is no longer in use for the following reasons:

• First, when you open a file in your script, the file system usually locks it down so no other programs or scripts can use it until you close it.
• Second, your file system has a limited number of file descriptors that you can create before it runs out of them. Although this number might be high, it’s possible to open a lot of files and deplete your file system resources.
• Third, leaving many files open may lead to race conditions which occur when multiple processes attempt to modify one file at the same time and can cause all kinds of unexpected behaviors.

The following shows how to call the close() method to close the file:

f.close()Code language: Python (python)

To close the file automatically without calling the close() method, you use the with statement like this:

with open(path_to_file) as f: contents = f.readlines()Code language: Python (python)

In practice, you’ll use the with statement to close the file automatically.

Reading a text file examples

We’ll use the-zen-of-python.txt file for the demonstration.

The following example illustrates how to use the read() method to read all the contents of the the-zen-of-python.txt file into a string:

with open('the-zen-of-python.txt') as f: contents = f.read() print(contents)Code language: Python (python)

Beautiful is better than ugly. Explicit is better than implicit. Simple is better than complex. . Code language: Python (python)

The following example uses the readlines() method to read the text file and returns the file contents as a list of strings:

with open('the-zen-of-python.txt') as f: [print(line) for line in f.readlines()]Code language: Python (python)

Beautiful is better than ugly. Explicit is better than implicit. Simple is better than complex. Complex is better than complicated. . Code language: Python (python)

The reason you see a blank line after each line from a file is that each line in the text file has a newline character (\n). To remove the blank line, you can use the strip() method. For example:

with open('the-zen-of-python.txt') as f: [print(line.strip()) for line in f.readlines()]Code language: Python (python)

The following example shows how to use the readline() to read the text file line by line:

with open('the-zen-of-python.txt') as f: while True: line = f.readline() if not line: break print(line.strip())Code language: Python (python)

Explicit is better than implicit. Complex is better than complicated. Flat is better than nested. . Code language: Python (python)

A more concise way to read a text file line by line

The open() function returns a file object which is an iterable object. Therefore, you can use a for loop to iterate over the lines of a text file as follows:

with open('the-zen-of-python.txt') as f: for line in f: print(line.strip())Code language: Python (python)

This is a more concise way to read a text file line by line.

Read UTF-8 text files

The code in the previous examples works fine with ASCII text files. However, if you’re dealing with other languages such as Japanese, Chinese, and Korean, the text file is not a simple ASCII text file. And it’s likely a UTF-8 file that uses more than just the standard ASCII text characters.

To open a UTF-8 text file, you need to pass the encoding=’utf-8′ to the open() function to instruct it to expect UTF-8 characters from the file.

For the demonstration, you’ll use the following quotes.txt file that contains some quotes in Japanese.

The following shows how to loop through the quotes.txt file:

with open('quotes.txt', encoding='utf8') as f: for line in f: print(line.strip())Code language: Python (python)

Summary

• Use the open() function with the ‘r’ mode to open a text file for reading.
• Use the read() , readline() , or readlines() method to read a text file.
• Always close a file after completing reading it using the close() method or the with statement.
• Use the encoding=’utf-8′ to read the UTF-8 text file.

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Read File as a String in Python

In this Python tutorial, you will learn how to read a file as a string, and the examples cover different scenarios like incorporating file checks before reading.

Python – Read File as String

You can read whole content of a file to a string in Python.

Generally, to read file content as a string, you follow these steps.

1. Open file in read mode. Call inbuilt open() function with file path as argument. open() function returns a file object.
2. Call read() method on the file object. read() method returns whole content of the file as a string.
3. Close the file by calling close() method on the file object.

The default mode is text mode for open() function. So, even if you do not provide any mode for open() function, the read operation should work fine.

Examples

In the following examples, we write Python programs to read the text file given by a path, and store it as a string value.

1. Read file as a string

In this example, we assume that we a file with two lines of content present in the location D:/data.txt . We shall apply the sequence of steps mentioned above, and read the whole content of file to a string.

Python Program

#open text file in read mode text_file = open("D:/data.txt", "r") #read whole file to a string data = text_file.read() #close file text_file.close() print(data)

Hello World! Welcome to www.tutorialkart.com.

2. Negative scenario – File path incorrect while reading the file

In this example, we assume that we are trying to read content of a file that is not present. In other words, file path is incorrect.

Python Program

#open text file in read mode text_file = open("D:/data123.txt", "r") #read whole file to a string data = text_file.read() #close file text_file.close() print(data)

Traceback (most recent call last): File "d:/workspace/fipics/rough.py", line 2, in text_file = open("D:/data123.txt", "r") FileNotFoundError: [Errno 2] No such file or directory: 'D:/data123.txt'

There is our FileNotFoundError. And the message says that no such file or directory with the file path passed to open() function.

3. Check if file is present before reading file to a string

In this example, before reading a file, we shall check if the file present. Only after we make a confirmation that the file present, we shall read its content to a string.

To check if a file is present, we use os.path.isfile() function.

Python Program

import os file_path = "D:/data123.txt" #check if file is present if os.path.isfile(file_path): #open text file in read mode text_file = open(file_path, "r") #read whole file to a string data = text_file.read() #close file text_file.close() print(data)

Now, try with the file paths that is present and not present. If the file is present, you read the text from file, else you don’t. But, no runtime error from Python Interpreter.

Conclusion

In this Python Tutorial, we learned how to read file content to a string.

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