我正在寻找一种在多行 Python 字符串中使用变量的干净方法。假设我想做以下事情:
string1 = go
string2 = now
string3 = great
"""
I will $string1 there
I will go $string2
$string3
"""
我想看看 Perl 中是否有类似于
$
的东西来指示 Python 语法中的变量。
如果不是 - 创建带有变量的多行字符串的最简洁方法是什么?
常用的方式是
format()
函数:
>>> s = "This is an {example} with {vars}".format(vars="variables", example="example")
>>> s
'This is an example with variables'
它适用于多行格式字符串:
>>> 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.
您还可以传递带有变量的字典:
>>> d = { 'vars': "variables", 'example': "example" }
>>> s = "This is an {example} with {vars}"
>>> s.format(**d)
'This is an example with variables'
最接近您要求的东西(就语法而言)是模板字符串。例如:
>>> from string import Template
>>> t = Template("This is an $example with $vars")
>>> t.substitute({ 'example': "example", 'vars': "variables"})
'This is an example with variables'
我应该补充一点,
format()
函数更常见,因为它很容易获得并且不需要导入行。
您可以将 Python 3.6 的 f-strings 用于多行或冗长的单行字符串中的变量。您可以使用
\n
手动指定换行符。
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)
我会去那里
我现在就去
太棒了
string1 = "go"
string2 = "now"
string3 = "great"
singleline_string = (f"I will {string1} there. "
f"I will go {string2}. "
f"{string3}.")
print(singleline_string)
我会去那里。我要走了。太棒了。
或者,您也可以创建带有三引号的多行 f 字符串。
multiline_string = f"""I will {string1} there.
I will go {string2}.
{string3}."""
注意:在Python中进行字符串格式化的推荐方法是使用
format()
,如接受的答案中所述。我保留这个答案作为也受支持的 C 风格语法的示例。
# 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)
一些阅读:
f-strings,也称为“格式化字符串文字”,是开头有
f
的字符串文字;和花括号包含将被其值替换的表达式。
f 字符串在运行时评估。
所以你的代码可以重写为:
string1="go"
string2="now"
string3="great"
print(f"""
I will {string1} there
I will go {string2}
{string3}
""")
这将评估为:
I will go there
I will go now
great
您可以在这里了解更多信息。
>>> 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
query = """
{{
pairs(block: {block} first: 200, orderBy: trackedReserveETH, orderDirection: desc) {{
id
txCount
reserveUSD
trackedReserveETH
volumeUSD
}}
}}
""".format(block=''.join(['{number: ', str(block), '}']))
query = gql(query)
确保像我一样转义所有花括号:“{{”,“}}”
dict = {'string1': 'go',
'string2': 'now',
'string3': 'great'}
multiline_string = '''I'm will {string1} there
I will go {string2}
{string3}'''.format(**dict)
print(multiline_string)
也可以将列表传递给format()
list = ['go',
'now',
'great']
multiline_string = '''I'm will {0} there
I will go {1}
{2}'''.format(*list)
print(multiline_string)
上述两种解决方案都会输出相同的结果:
我会去那里我现在就去
太棒了
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}")
这对我有用。也许它对某人有帮助,干杯
string1 = "go"
string2 = "now"
string3 = "great"
s = f"""
I will {string1} there
I will go {string2}
{string3}
"""
print(s)
这将会回归。
I will go there
I will go now
great
希望这有帮助。
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