#Python open readwrite how to

Print(file.readlines()) How to use a for loop to read lines from a file in PythonĪn alternative to these different read methods would be to use a for loop. In this example, we are going to print out our grocery items as a list using the readlines() method.

This method will read and return a list of all of the lines in the file. Print(file.readline(7)) What is the readlines() method in Python? We can modify the example to add the number 7 to only read and print out This is: with open('demo.txt') as file: This method also takes in the optional size parameter.

If we use the readline() method, it will only print the first sentence of the file. In this example, we have a text file with these two sentences: This is the first line This method is going to read one line from the file and return that. Print(file.read()) What is the readline() method in Python? Here is how to rewrite our example using the with keyword: with open('demo.txt') as file: This is considered good practice, because the file will close automatically instead of you having to manually close it. One way to ensure that your file is closed is to use the with keyword. This is an example of how to close the demo.txt file: file = open('demo.txt')įile.close() How to use the with keyword to close files in Python If you forget to close your file, then that can cause issues. Once you are done reading a file, it is important that you close it. If the size argument is omitted, or if the number is negative, then the whole file will be read. If we modify the earlier example, we can print out only the first word by adding the number 4 as an argument for read().

Instead of reading the whole file, only a portion of it will be read. This method can take in an optional parameter called size. In this example, I am using the read() method to print out a list of names from the demo.txt file: file = open('demo.txt') This is a good method to use if you don't have a lot of content in the text file. The read() method is going to read all of the content of the file as one string. Print(file.readable()) What is the read() method in Python? If I changed this example, to 'w' (write) mode, then the readable() method would return False: file = open('demo.txt', 'w') This example would return True because we are in the read mode: file = open('demo.txt') If you want to check if a file can be read, then you can use the readable() method.

To learn more about these optional parameters, please read through the documentation. The open() function can take in these optional parameters. Additional parameters for the open() function in Python I am not going to go into detail for the other modes because we are just going to focus on reading files.įor a complete list of the other modes, please read through the documentation. There are other types of modes such as 'w' for writing or 'a' for appending. You can also omit mode= and just write 'r'. There are different modes when you are working with files. It is really important to keep track of which directory you are in so you can reference the correct path name. If you don't have the correct path for the file, then you will get an error message like this: open('random-text.txt') In order to access that file in the main.py, you have to include the folder name with the name of the file. In this example, the random-text file is inside a different folder then main.py: If your text file is in a different directory, then you will need to reference the correct path name for the text file. Here is an example of both files being in the same directory: If the text file and your current file are in the same directory ('folder'), then you can just reference the file name in the open() function. This is the basic syntax for Python's open() function: open('name of file you want opened', 'optional mode') File names and correct paths If you want to read a text file in Python, you first have to open it.

In this article, I will go over the open() function, the read(), readline(), readlines(), close() methods, and the with keyword. In Python, there are a few ways you can read a text file.

Python open readwrite