Only Read in Number From a List Python

In Python, there are a few ways you tin read a text file.

In this article, I will become over the open() part, the read(), readline(), readlines(), close() methods, and the with keyword.

What is the open() function in Python?

If you want to read a text file in Python, you outset accept to open it.

This is the basic syntax for Python'due south open() part:

                open("name of file you lot desire opened", "optional mode")              

File names and correct paths

If the text file and your electric current file are in the aforementioned directory ("folder"), then you can just reference the file name in the open() function.

                open("demo.txt")              

Here is an example of both files being in the aforementioned directory:

If your text file is in a different directory, then you lot will need to reference the correct path proper noun for the text file.

In this example, the random-text file is inside a different binder then main.py:

In order to admission that file in the chief.py, yous accept to include the binder name with the proper noun of the file.

                open("text-files/random-text.txt")              

If you don't accept the correct path for the file, then you will become an mistake bulletin like this:

                open up("random-text.txt")              

It is really of import to keep track of which directory you are in and so you can reference the correct path name.

Optional Mode parameter in open up()

At that place are different modes when you are working with files. The default mode is the read manner.

The letter of the alphabet r stands for read mode.

                open("demo.txt", mode="r")              

You tin can besides omit mode= and only write "r".

                open up("demo.txt", "r")              

In that location are other types of modes such as "westward" for writing or "a" for appending.  I am non going to go into particular for the other modes because we are just going to focus on reading files.

For a complete list of the other modes, delight read through the documentation.

Additional parameters for the open() function in Python

The open() office can accept in these optional parameters.

• buffering
• encoding
• errors
• newline
• closefd
• opener

To acquire more nearly these optional parameters, please read through the documentation.

What is the readable() method in Python?

If you want to check if a file can be read, then you lot tin can utilise the readable() method. This will render a True or Fake.

This case would return True considering we are in the read mode:

                file = open up("demo.txt") print(file.readable())              

If I inverse this example, to "west" (write) style, then the readable() method would render Faux:

                file = open("demo.txt", "w") print(file.readable())              

What is the read() method in Python?

The read() method is going to read all of the content of the file as i string. This is a good method to use if you don't have a lot of content in the text file.

In this instance, I am using the read() method to print out a list of names from the demo.txt file:

                file = open("demo.txt") print(file.read())              

This method can take in an optional parameter called size. Instead of reading the whole file, but a portion of information technology will be read.

If we alter the before example, we can impress out but the first word past calculation the number 4 equally an argument for read().

                file = open("demo.txt") print(file.read(4))              

If the size argument is omitted, or if the number is negative, then the whole file will exist read.

What is the close() method in Python?

Once you are done reading a file, it is important that you close it. If you forget to shut your file, then that tin can cause bug.

This is an example of how to close the demo.txt file:

                file = open("demo.txt") print(file.read()) file.close()              

How to use the with keyword to close files in Python

One way to ensure that your file is closed is to apply the with keyword. This is considered good practice, because the file will shut automatically instead of you having to manually shut information technology.

Hither is how to rewrite our example using the with keyword:

                with open("demo.txt") as file:     impress(file.read())              

What is the readline() method in Python?

This method is going to read one line from the file and return that.

In this example, we have a text file with these two sentences:

                This is the offset line This is the second line              

If we use the readline() method, it will simply print the showtime sentence of the file.

                with open("demo.txt") equally file:     print(file.readline())              

This method also takes in the optional size parameter. We can modify the example to add the number 7 to merely read and print out This is:

                with open("demo.txt") every bit file:     impress(file.readline(7))              

What is the readlines() method in Python?

This method will read and return a list of all of the lines in the file.

In this example, we are going to print out our grocery items as a list using the readlines() method.

                with open("demo.txt") as file:     print(file.readlines())              

How to use a for loop to read lines from a file in Python

An alternative to these different read methods would be to utilize a for loop.

In this instance, we tin print out all of the items in the demo.txt file by looping over the object.

                with open up("demo.txt") equally file:     for detail in file:         print(detail)              

Conclusion

If you lot want to read a text file in Python, you beginning accept to open it.

                open("name of file you want opened", "optional fashion")                              

If the text file and your current file are in the same directory ("folder"), and so you tin can just reference the file proper name in the open() role.

If your text file is in a dissimilar directory, and then you lot will demand to reference the right path name for the text file.

The open up() part takes in the optional mode parameter. The default mode is the read mode.

                open("demo.txt", "r")              

If yous want to check if a file tin exist read, then you tin can utilize the readable() method. This will return a True or Imitation.

                file.readable()              

The read() method is going to read all of the content of the file equally one string.

                file.read()              

Once you are washed reading a file, information technology is of import that you close it. If you forget to shut your file, then that tin crusade issues.

                file.close()              

Ane way to ensure that your file is closed is to use the with keyword.

                with open("demo.txt") as file:     print(file.read())              

The readline() method is going to read one line from the file and return that.

                file.readline()              

The readlines() method volition read and return a listing of all of the lines in the file.

                file.readlines()              

An alternative to these different read methods would be to utilize a for loop.

                with open("demo.txt") every bit file:     for item in file:         impress(item)              

I hope y'all enjoyed this article and best of luck on your Python journeying.

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