Python write lines to output file

Python Write To File Line By Line:

Python Write To File Line By Line Using writelines():

Here in the first line, we defined a list in a variable called ‘numbers’. you can give any name to this variable. and we are opening the devops.txt file and appending lines to the text file. in python writelines(), module need a list of data to write. so we mentioned variable ‘numbers’ in writelines() function and in the last line we closed the opened file

numbers = ["One\n", "Two\n", "Three\n", "Four\n", "Five\n"] F = open("devops.txt", "a") F.writelines(numbers) F.close()

Output:

Python Write To File Line By Line Using writelines() and For Loop:

lines = ['line1', 'line2',"line3"] f=open('devops.txt', 'a') f.writelines("%s\n" % i for i in lines) f.close()

here in the first line we defined a list with varaible lines. and in the second line, we are opening the file to append the new lines. and then by using writelines() function we are sending the list to the file line by line. writelines function in python needs a list. so here we are sending list ‘lines’ to writelines() by using for loop.

Output:

or Opening a File In a Different Way:

lines = ['line1', 'line2'] with open('devops.txt', 'a') as f: f.writelines("%s\n" % l for l in lines)

here we used the same code as above but to open the file and append we used a different method.

Output:

Python Write To File Line By Line Using write() and For Loop:

abc = ["One", "Two", "Three", "Four", "Five"] x = open("devops.txt", "a") for i in abc: x.write('\n%s' % i) x.close()

here in the first line, we defined our list which needs to add to our text file. and the second line we opened the file and appending data into that file. in the third and fourth line, we defined a for loop to write data into that file line by line. here you can see \n it will add a new line in the beginning only so our new appending data will add as a new line.

output:

Read a file line by line and write this lines into new file

with open("devops.txt","r") as d: x=d.readlines() with open("new.txt","w") as f: f.writelines(x) f.close()

above code will read the devops.txt file line by line and write intoto another file called new.txt. So the both files will be look similar.

This entry was posted in python and tagged Python Write To File Line By Line. Bookmark the permalink.

Источник

How to Write Line to File in Python

To write a line to a file in Python, you can use the “with statement” along with the “open()” function in write mode (‘w’). The with statement helps you to close the file without explicitly closing it. This is the correct way to write a line to the file. The with statement is used to wrap the execution of a block with methods defined by a context manager.

Example 1: How to write a line to a file

If the file does not exist, the open() function will create a new file. If the file exists and you want to append the new content, then while creating a file, use the “a” mode. Use the “w” to write with truncation.

with open('data.txt', 'a') as f: f.write('Welcome Playstation 5\n')

It will create a new file called data.txt with the following content.

Alternatively, you can use the print() function instead of the write() function.

with open('data.txt', 'a') as f: print("hey there", file=f)

It will create a new file called data.txt with the following content.

The write() function is more efficient than the print() function. So my recommendation is to use the write() function to write the lines in the file.

How to write multiple lines to a file in Python

To write multiple lines to a file in Python, you can use the “with open()” expression and then the writelines() function. The writelines() method writes the items of a list to the file. The texts will be inserted depending on the file mode and stream position.

Syntax of writelines()

Parameters

Example

with open('data.txt', 'a') as f: line1 = "PS5 Restock India \n" line2 = "Xbox Series X Restock India \n" line3 = "Nintendo Switch Restock India" f.writelines([line1, line2, line3])

The output will be a data.txt file with the following content.

PS5 Restock India Xbox Series X Restock India Nintendo Switch Restock India

As you can see that we wrote three lines in a newly created file.

Источник

3 Ways to Write Text to a File in Python

If you are interested in writing text to a file in Python, there is probably many ways to do it. Here is three ways to write text to a output file in Python. The first step in writing to a file is create the file object by using the built-in Python command “open”. To create and write to a new file, use open with “w” option. The “w” option will delete any previous existing file and create a new file to write.

# open a (new) file to write outF = open("myOutFile.txt", "w")

If you want to append to an existing file, then use open statement with “a” option. In append mode, Python will create the file if it does not exist.

# open a file to append outF = open("myOutFile.txt", "a")

Once you have created the file object in write/append mode, you can write text in multiple ways. Let us say we have the text that we want to write is in a list “textList”.

textList = ["One", "Two", "Three", "Four", "Five"]

We can write this list to a file either line by line or write all lines at once.

Writing One Line at a Time to a File in Python Using write()

Let us create new file by creating the file object “outF” using “w” option as before. To write line by line, we loop through the textList and get each element and write it to the file.

outF = open("myOutFile.txt", "w") for line in textList: # write line to output file outF.write(line) outF.write("\n") outF.close()

Note that the elements in the “textList” does not have a new line character “\n”. Therefore, we added that while writing to the file. Otherwise, all five elements will be in a single line in the output file. Also note outF.close() at the end. close() method closes the access to the file. It is a good practice to use the close() method to close a file, once we are done with a file.

Writing One Line at a Time to a File in Python Using “print”

Another way to write one line at a time to a file in Python is to use the print statement. Instead of printing a statement to the scree, we redirect to the output file object.

outF = open("myOutFile.txt", "w") for line in textList: print >>outF, line outF.close()

writelines(): Writing All The Lines at a Time to a File in Python

Python also has a method that can write all lines at the same time to a file. Python’s “writelines()” method takes a list of lines as input and writes to a file object that is open with write/append access. For example to write our list of all line “all_lines”, using “writelines().

outF = open("myOutFile.txt", "w") outF.writelines(all_lines) outF.close()

We can also make our lives easier without writing file.close() statement by using with statement to write to a file. For example,

with open(out_filename, 'w') as out_file: .. .. .. parsed_line out_file.write(parsed_line)

If you are interested in reading from a text file, check Three ways to read a text file line by line in python.

Источник