Read first lines python

How to Read only the First Line of the File?

In this article, we will learn how one can read the first line only from a file in Python. We will use some built-in functions, some simple approaches, and some custom codes as well to better understand the topic.

Python handles various file operations. In the case of reading files, if the user wants to read only the first line or maybe a header, Python provides readline() function for it. Let us discuss three different methods to read the first line of the file. We will read the first line of the given sample.txt file.

Sample Text File

It is an exciting time to be a book reviewer. Once confined to print newspapers and journals, reviews now dot many corridors of the Internet forever helping others discover their next great read.

Example: Read the First Line using next()

We use the sample.txt file to read the first line. We open the file in read mode and uses next() to store the first line in a variable. The below code uses strip() function to remove extra newline characters. You can remove it according to your need.

with open('sample.txt', 'r') as f: first_line = next(f).strip() print(first_line)

It is an exciting time to be a book reviewer.

Example: Read the First Line using readlines()

We use the sample.txt file to read the contents. This method uses readlines() to store the first line. readlines() uses the slicing technique. As you can see in the below example, firstline[0].strip() , it denotes the stripping of newlines spaces from index 0. This is a much more powerful solution as it generalizes to any line. The drawback of this method is that it works fine for small files but can create problems for large files.

with open('sample.txt', 'r') as f: first_line = f.readlines() print(first_line[0].strip())

It is an exciting time to be a book reviewer.

Example: Read the First Line using readline()

We use the sample.txt file to read the contents. This is an efficient and pythonic way of solving the problem. This even works for in-memory uploaded files while iterating over file objects. This simply uses readline() to print the first line.

with open('sample.txt', 'r') as f: first_line = f.readline().strip() print(first_line)

It is an exciting time to be a book reviewer.

Note: Observe your output when you run the above code snippets without strip() function. You will notice an empty line along with the first line.

Conclusion

In this article, we learned to read the first line of the file by using several built-in functions such as next() , readlines() , readline() and different examples to read the first line from the given file.

Источник

Read First Line of a File in Python

1. Use the read() Function to Read the First Line of a File in Python
2. Use the readline() Function to Read the First Line of File in Python
3. Use the readlines() Function to Read the First Line of a File in Python
4. Use the next() Function to Read the First Line of a File in Python

In Python, we have built-in functions that can handle different file operations. A Text file contains a sequence of strings in which every line terminated using a newline character \n .

In this tutorial, we will learn how to read the first line of a text file in Python.

We can use the open() function to create a file object by passing the file path to the function and open a file in a specific mode, read mode by default.

Use the read() Function to Read the First Line of a File in Python

The read() function is used to read the data from a file. To extract the first line from the file, we can simply use the split() function to get a list of all the lines separated based on the newline character, and extract the first line from this list. For example:

with open("sample.txt") as f:  lines = f.read() ##Assume the sample file has 3 lines  first = lines.split('\n', 1)[0]  print(first) 

Use the readline() Function to Read the First Line of File in Python

Another method to read the first line of a file is using the readline() function that reads one line from the stream.

with open("sample.txt") as f:  firstline = f.readline().rstrip()  print(firstline) 

Notice that we use the rstrip() function to remove the newline character at the end of the line because readline() returns the line with a trailing newline.

Use the readlines() Function to Read the First Line of a File in Python

We can also use the readlines() function, which reads all the lines from the file and returns a list of each line as the list item, and then extract the first line from the returned list. For example:

with open("sample.txt") as f:  firstline = f.readlines()[0].rstrip()  print(firstline) 

Use the next() Function to Read the First Line of a File in Python

An unconventional method of achieving the same is by using the next() function. It returns the next item in an iterator. So if we pass the file object to the next() function, it returns the first line of the file. For example:

with open("sample.txt") as f:  firstline = next(f)  print(firstline) 

Manav is a IT Professional who has a lot of experience as a core developer in many live projects. He is an avid learner who enjoys learning new things and sharing his findings whenever possible.

Related Article — Python File

Источник

Read First Line of File Using Python

To read the first line of a file in Python, the easiest way is with the Python file readline() function.

with open("example.txt") as f: first_line = f.readline()

You can also use the Python readlines() function and access the first item to get the first line of a file.

with open("example.txt") as f: first_line = f.readlines()[0]

One other way you can read the first line of a file is with the read() function and then split it on the new line character.

with open("example.txt") as f: lines = f.read() first_line = lines.split("/n")[0]

One last way you can read the first line of a file is with the next() function.

with open("example.txt") as f: first_line = next(f)

When working with files, the ability to easily read from or write to a file is valuable.

One such case is if you want to just read the first line of a file.

There are a number of different ways you can read the first line from a file in Python.

The easiest way, in our opinion, is with the file readline() function. readline() returns one line from the file. If you use readline() directly after opening the file, you will be able to read the contents of the first line.

Below is an example showing how you can get the first line of a file using readline() in Python.

with open("example.txt") as f: first_line = f.readline()

Using readlines() Function in Python to Read First Line of File

Another way you can read the first line of a file is with the readlines() function. readlines() reads all of the lines and returns a list.

After using readlines(), you can get the first element of the list, which will be the first line of the file.

Below is an example showing how you can get the first line of a file using readlines() in Python.

with open("example.txt") as f: first_line = f.readlines()[0]

Using read() and split() in Python to Read First Line of File

Another way you can read the first line of a file is with the read() function.

read() reads the entire file you are working with.

After reading the entire file with read(), you can use split() to split the file by the newline character and get the lines.

After this, you have a list with the lines of the file and you can again access the first element of the list of lines.

Below is an example showing how you can get the first line of a file using read() and split() in Python.

with open("example.txt") as f: lines = f.read() first_line = lines.split("/n")[0]

Using Python next() function to Read First Line of File

One last way you can get the first line of a file is with the next() function.

When you open a file, you get a generator and can use the next() function. Since the first line is the next line after you’ve opened a file, then you can get the first line with next().

Below is an example showing how you can get the first line of a file using next() in Python.

with open("example.txt") as f: first_line = next(f)

Hopefully this article has been useful for you to learn how to read the first line from a file in your Python programs.

Other Articles You’ll Also Like:

• 1. Python sin – Find Sine of Number in Radians Using math.sin()
• 2. Selenium minimize_window() Function to Minimize Window in Python
• 3. Python power function – Exponentiate Numbers with math.pow()
• 4. Change Column Name in pandas DataFrame
• 5. pandas Duplicated – Find Duplicate Rows in DataFrame or Series
• 6. Python Decrement Counter with -= Decrement Operator
• 7. Using Python to Find Maximum Value in List
• 8. Check if String Contains Numbers in Python
• 9. Open Multiple Files Using with open in Python
• 10. Using Python to Check if Queue is Empty

About The Programming Expert

The Programming Expert is a compilation of a programmer’s findings in the world of software development, website creation, and automation of processes.

Programming allows us to create amazing applications which make our work more efficient, repeatable and accurate.

At the end of the day, we want to be able to just push a button and let the code do it’s magic.

You can read more about us on our about page.

Источник

How to Read the First Line of a File in Python

This article will show you how to read and display the first line of a file in Python.

For this article, we will work with a flat-text file containing five (5) possible things to do during your lifetime. This file is saved to bucket_list.txt and placed into the current working directory.

1	Bring a Fishing Pole to an Aquarium.
2	Call Someone To Tell Them You Can’t Talk Right Now.
3	Send a Hogwarts acceptance letter to a random address and see if they respond.
4	Switch Your Friends Phone To A Foreign Language.
5	Create a Piece of Art and Put it on Etsy for $1,000,000.

💬 Question: How would we write code to retrieve the first line of a file?

We can accomplish this task by one of the following options:

Method 1: Use readline() and strip()

This method uses Python’s built-in readline() function. This function reads a single line from the file.

with open('bucket_list.txt', 'r') as fp: first_item = fp.readline().strip() print(first_item)

The first line in the above code opens the bucket_list.txt file in read ( r ) mode and creates a File Object ( fp ) of the same. This object allows us access to and manipulation of files. If output to the terminal, an object similar to the one below would display.

The following line references fp and appends readline() to read in the first line of said file. Next, strip() is applied to remove extraneous spaces and newline characters from the line. The results save to first_line and output to the terminal.

1 Bring a Fishing Pole to an Aquarium.

At university, I found my love of writing and coding. Both of which I was able to use in my career.

During the past 15 years, I have held a number of positions such as:

In-house Corporate Technical Writer for various software programs such as Navision and Microsoft CRM
Corporate Trainer (staff of 30+)
Programming Instructor
Implementation Specialist for Navision and Microsoft CRM
Senior PHP Coder

Be on the Right Side of Change 🚀

• The world is changing exponentially. Disruptive technologies such as AI, crypto, and automation eliminate entire industries. 🤖
• Do you feel uncertain and afraid of being replaced by machines, leaving you without money, purpose, or value? Fear not! There a way to not merely survive but thrive in this new world!
• Finxter is here to help you stay ahead of the curve, so you can keep winning as paradigms shift.

Learning Resources 🧑‍💻

⭐ Boost your skills. Join our free email academy with daily emails teaching exponential with 1000+ tutorials on AI, data science, Python, freelancing, and Blockchain development!

Join the Finxter Academy and unlock access to premium courses 👑 to certify your skills in exponential technologies and programming.

New Finxter Tutorials:

Finxter Categories:

Источник