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
"""
I will $string1 there
I will go $string2
$string3
"""
I’m looking to see if there is something similar to $ in Perl to indicate a variable in the Python syntax.
If not – what is the cleanest way to create a multiline string with variables?
Answers:
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:
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.
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} therenI 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
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
You can use Python 3.6’s f-strings for variables inside multi-line or lengthy single-line strings. You can manually specify newline characters using n.
Variables in a multi-line string
string1 = "go"
string2 = "now"
string3 = "great"
multiline_string = (f"I will {string1} theren"
f"I will go {string2}.n"
f"{string3}.")
print(multiline_string)
I will go there
I will go now
great
Variables in a lengthy single-line string
string1 = "go"
string2 = "now"
string3 = "great"
singleline_string = (f"I will {string1} there. "
f"I will go {string2}. "
f"{string3}.")
print(singleline_string)
I will go there. I will go now. great.
Alternatively, you can also create a multiline f-string with triple quotes.
multiline_string = f"""I will {string1} there.
I will go {string2}.
{string3}."""
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: "{{", "}}"
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.
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
"""
I will $string1 there
I will go $string2
$string3
"""
I’m looking to see if there is something similar to $ in Perl to indicate a variable in the Python syntax.
If not – what is the cleanest way to create a multiline string with variables?
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:
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.
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} therenI 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
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
You can use Python 3.6’s f-strings for variables inside multi-line or lengthy single-line strings. You can manually specify newline characters using n.
Variables in a multi-line string
string1 = "go"
string2 = "now"
string3 = "great"
multiline_string = (f"I will {string1} theren"
f"I will go {string2}.n"
f"{string3}.")
print(multiline_string)
I will go there
I will go now
great
Variables in a lengthy single-line string
string1 = "go"
string2 = "now"
string3 = "great"
singleline_string = (f"I will {string1} there. "
f"I will go {string2}. "
f"{string3}.")
print(singleline_string)
I will go there. I will go now. great.
Alternatively, you can also create a multiline f-string with triple quotes.
multiline_string = f"""I will {string1} there.
I will go {string2}.
{string3}."""
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: "{{", "}}"
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.