How do I create a multiline Python string with inline variables?

Question

I am looking for a clean way to use variables within a multiline Python string. Say I wanted to do the following:

string1 = go
string2 = now
string3 = great
         


        

Answer 1

The common way is the format() function:

>>> s = "This is an {example} with {vars}".format(vars="variables", example="example")
>>> s
'This is an example with variables'

It works fine with a multi-line format string:

>>> s = '''\
... This is a {length} example.
... Here is a {ordinal} line.\
... '''.format(length='multi-line', ordinal='second')
>>> print(s)
This is a multi-line example.
Here is a second line.

You can also pass a dictionary with variables:

>>> d = { 'vars': "variables", 'example': "example" }
>>> s = "This is an {example} with {vars}"
>>> s.format(**d)
'This is an example with variables'

The closest thing to what you asked (in terms of syntax) are template strings. For example:

>>> from string import Template
>>> t = Template("This is an $example with $vars")
>>> t.substitute({ 'example': "example", 'vars': "variables"})
'This is an example with variables'

I should add though that the format() function is more common because it's readily available and it does not require an import line.

Answer 2

NOTE: The recommended way to do string formatting in Python is to use format(), as outlined in the accepted answer. I'm preserving this answer as an example of the C-style syntax that's also supported.

# NOTE: format() is a better choice!
string1 = "go"
string2 = "now"
string3 = "great"

s = """
I will %s there
I will go %s
%s
""" % (string1, string2, string3)

print(s)

Some reading:

• String formatting
• PEP 3101 -- Advanced String Formatting

Answer 3

f-strings, also called “formatted string literals,” are string literals that have an f at the beginning; and curly braces containing expressions that will be replaced with their values.

f-strings are evaluated at runtime.

So your code can be re-written as:

string1="go"
string2="now"
string3="great"
print(f"""
I will {string1} there
I will go {string2}
{string3}
""")

And this will evaluate to:

I will go there
I will go now
great

You can learn more about it here.

Answer 4

If anyone came here from python-graphql client looking for a solution to pass an object as variable here's what I used:

query = """
{{
  pairs(block: {block} first: 200, orderBy: trackedReserveETH, orderDirection: desc) {{
    id
    txCount
    reserveUSD
    trackedReserveETH
    volumeUSD
  }}
}}
""".format(block=''.join(['{number: ', str(block), '}']))

 query = gql(query)

Make sure to escape all curly braces like I did: "{{", "}}"

Answer 5

This is what you want:

>>> string1 = "go"
>>> string2 = "now"
>>> string3 = "great"
>>> mystring = """
... I will {string1} there
... I will go {string2}
... {string3}
... """
>>> locals()
{'__builtins__': <module '__builtin__' (built-in)>, 'string3': 'great', '__package__': None, 'mystring': "\nI will {string1} there\nI will go {string2}\n{string3}\n", '__name__': '__main__', 'string2': 'now', '__doc__': None, 'string1': 'go'}
>>> print(mystring.format(**locals()))

I will go there
I will go now
great

Answer 6

A dictionary can be passed to format(), each key name will become a variable for each associated value.

dict = {'string1': 'go',
        'string2': 'now',
        'string3': 'great'}

multiline_string = '''I'm will {string1} there
I will go {string2}
{string3}'''.format(**dict)

print(multiline_string)

Also a list can be passed to format(), the index number of each value will be used as variables in this case.

list = ['go',
        'now',
        'great']

multiline_string = '''I'm will {0} there
I will go {1}
{2}'''.format(*list)

print(multiline_string)

Both solutions above will output the same:

I'm will go there
I will go now
great