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?
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.
vars() or locals() as the dictionary in question
dict anyway.
{{this}}.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.
string1 = "go"
string2 = "now"
string3 = "great"
multiline_string = (
f"I will {string1} there\n"
f"I will go {string2}.\n"
f"{string3}."
)
print(multiline_string)
I will go there
I will go now
great
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 where literal newlines are considered part of the string. However, any spaces at the start of the line would also be part of the string, so it can mess with code indentation.
multiline_string = f"""I will {string1} there.
I will go {string2}.
{string3}."""
+ to concatenate): stackoverflow.com/a/54564926/4561887
f prefix to enable formatting inline. But I like this approach for multi-inline formatting.
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:
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.
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: "{{", "}}"
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
""" preserves newlines, which means there is an extra newline before and after mystring
.strip(), .rstrip() or .lstrip(), or ue a backlash inside the triple quotes to avoid creating a newline. mystring = """\ ABC\ """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
Simplest way is to use f-string multiline.
string1 = "go"
string2 = "now"
string3 = "great"
s = f"""
I will {string1} there
I will go {string2}
{string3}
"""
print(s)
This will return.
I will go there
I will go now
great
Hope this helps.
print (f" \
What you want to write {var_one} \n \
What you want to write {var_two} \n \
What you want to write {var_three} \n \
Et cetera {var_four}")
This was what was working for me. Maybe it helps someone, cheers
Here is an example to break a string into multiple lines in a @dataclass for use with QT style sheets. The end of each line needs to be terminate in double quote followed by a slash, except for the last line. Indentation of the start of each line is also critical.
@dataclass
class button_a:
i: str = "QPushButton:hover {background: qradialgradient(cx:0, cy:0, radius:1,fx:0.5,fy:0.5,stop:0 white, stop:1 green);"\
"color:qradialgradient(cx:0, cy:0, radius:1,fx:0.5,fy:0.5,stop:0 yellow, stop:1 brown);"\
"border-color: purple;}"
