How do I specify new lines on Python, when writing on files?

In comparison to Java (in a string), you would do something like "First LinernSecond Line".

So how would you do that in Python, for purposes of writing multiple lines to a regular file?

13 Answers

It depends on how correct you want to be. n will usually do the job. If you really want to get it right, you look up the newline character in the os package. (It’s actually called linesep.)

Note: when writing to files using the Python API, do not use the os.linesep. Just use n; Python automatically translates that to the proper newline character for your platform.

The new line character is n. It is used inside a string.

Example:

    print('First line n Second line') 

where n is the newline character.

This would yield the result:

First line
 Second line

If you use Python 2, you do not use the parentheses on the print function.

You can either write in the new lines separately or within a single string, which is easier.

Example 1

Input

line1 = "hello how are you"
line2 = "I am testing the new line escape sequence"
line3 = "this seems to work"

You can write the ‘n’ separately:

file.write(line1)
file.write("n")
file.write(line2)
file.write("n")
file.write(line3)
file.write("n")

Output

hello how are you
I am testing the new line escape sequence
this seems to work

Example 2

Input

As others have pointed out in the previous answers, place the n at the relevant points in your string:

line = "hello how are younI am testing the new line escape sequencenthis seems to work"

file.write(line)

Output

hello how are you
I am testing the new line escape sequence
this seems to work

If you are entering several lines of text at once, I find this to be the most readable format.

file.write("
Life's but a walking shadow, a poor playern
That struts and frets his hour upon the stagen
And then is heard no more: it is a talen
Told by an idiot, full of sound and fury,n
Signifying nothing.n
")

The at the end of each line escapes the new line (which would cause an error).

In Python you can just use the new-line character, i.e. n

Platform independent line breaker: Linux,windows & IOS

import os
keyword = 'physical'+ os.linesep + 'distancing'
print(keyword)

Output:

physical
distancing

Simplest solution

If you only call print without any arguments, it will output a blank line.

print

You can pipe the output to a file like this (considering your example):

f = open('out.txt', 'w')
print 'First line' >> f
print >> f
print 'Second line' >> f
f.close()

Not only is it OS-agnostic (without even having to use the os package), it’s also more readable than putting n within strings.

Explanation

The print() function has an optional keyword argument for the end of the string, called end, which defaults to the OS’s newline character, for eg. n. So, when you’re calling print('hello'), Python is actually printing 'hello' + 'n'. Which means that when you’re calling just print without any arguments, it’s actually printing '' + 'n', which results in a newline.

Alternative

Use multi-line strings.

s = """First line
    Second line
    Third line"""
f = open('out.txt', 'w')
print s >> f
f.close()

The same way with 'n', though you’d probably not need the 'r'. Is there a reason you have it in your Java version? If you do need/want it, you can use it in the same way in Python too.

Most escape characters in string literals from Java are also valid in Python, such as “r” and “n”.

n – simple newline character insertion works:

# Here's the test example - string with newline char:
In [36]: test_line = "Hi!!!n testing first line.. n testing second line.. n and third line....."

# Output:
In [37]: print(test_line)

Hi!!!
 testing first line..
 testing second line..
 and third line.....

As mentioned in other answers: “The new line character is n. It is used inside a string”.

I found the most simple and readable way is to use the “format” function, using nl as the name for a new line, and break the string you want to print to the exact format you going to print it:

python2:

print("line1{nl}"
      "line2{nl}"
      "line3".format(nl="n"))

python3:

nl = "n"
print(f"line1{nl}"
      f"line2{nl}"
      f"line3")

That will output:

line1
line2
line3

This way it performs the task, and also gives high readability of the code 🙂

Worth noting that when you inspect a string using the interactive python shell or a Jupyter notebook, the n and other backslashed strings like t are rendered literally:

>>> gotcha = 'Here is some random message...'
>>> gotcha += 'nAdditional content:nt{}'.format('Yet even more great stuff!')
>>> gotcha
'Here is some random message...nAdditional content:ntYet even more great stuff!'

The newlines, tabs, and other special non-printed characters are rendered as whitespace only when printed, or written to a file:

>>> print('{}'.format(gotcha))
Here is some random message...
Additional content:
    Yet even more great stuff!

n separates the lines of a string. In the following example, I keep writing the records in a loop. Each record is separated by n.

f = open("jsonFile.txt", "w")

for row_index in range(2, sheet.nrows):

  mydict1 = {
    "PowerMeterId" : row_index + 1,
    "Service": "Electricity",
    "Building": "JTC FoodHub",
    "Floor": str(Floor),
    "Location": Location,
    "ReportType": "Electricity",
    "System": System,
    "SubSystem": "",
    "Incomer": "",
    "Category": "",
    "DisplayName": DisplayName,
    "Description": Description,
    "Tag": tag,
    "IsActive": 1,
    "DataProviderType": int(0),
    "DataTable": ""
  }
  mydict1.pop("_id", None)
  f.write(str(mydict1) + 'n')

f.close()

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