带有百分号的 Python 字符串格式
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Python string formatting with percent sign
提问by Sait
I am trying to do exactly the following:
我正在尝试执行以下操作：
>>> x = (1,2)
>>> y = 'hello'
>>> '%d,%d,%s' % (x[0], x[1], y)
'1,2,hello'
However, I have a long x, more than two items, so I tried:
但是，我有一个很长的x，超过两个的项目，所以我尝试了：
>>> '%d,%d,%s' % (*x, y)
but it is syntax error. What would be the proper way of doing this without indexing like the first example?
但它是语法错误。没有像第一个例子那样索引的正确方法是什么？
采纳答案by falsetru
str % ..accepts a tuple as a right-hand operand, so you can do the following:
str % ..接受元组作为右手操作数，因此您可以执行以下操作：
>>> x = (1, 2)
>>> y = 'hello'
>>> '%d,%d,%s' % (x + (y,)) # Building a tuple of `(1, 2, 'hello')`
'1,2,hello'
Your try should work in Python 3. where Additional Unpacking Generalizationsis supported, but not in Python 2.x:
您的尝试应该在 Python 3 中工作。Additional Unpacking Generalizations支持的地方，但在 Python 2.x 中不支持：
>>> '%d,%d,%s' % (*x, y)
'1,2,hello'
回答by plamut
Perhaps have a look at str.format().
也许看看str.format()。
>>> x = (5,7)
>>> template = 'first: {}, second: {}'
>>> template.format(*x)
'first: 5, second: 7'
Update:
更新：
For completeness I am also including additional unpacking generalizationsdescribed by PEP 448. The extended syntax was introduced in Python 3.5, and the following is no longer a syntax error:
为了完整起见，我还包括了PEP 448描述的其他解包概括。Python 3.5中引入了扩展语法，以下不再是语法错误：
>>> x = (5, 7)
>>> y = 42
>>> template = 'first: {}, second: {}, last: {}'
>>> template.format(*x, y) # valid in Python3.5+
'first: 5, second: 7, last: 42'
In Python 3.4 and below, however, if you want to pass additional arguments after the unpacked tuple, you are probably best off to pass them as named arguments:
但是，在Python 3.4 及以下版本中，如果您想在解包的元组之后传递额外的参数，您可能最好将它们作为命名参数传递：
>>> x = (5, 7)
>>> y = 42
>>> template = 'first: {}, second: {}, last: {last}'
>>> template.format(*x, last=y)
'first: 5, second: 7, last: 42'
This avoids the need to build a new tuple containing one extra element at the end.
这避免了在末尾构建一个包含一个额外元素的新元组的需要。
回答by Fabio Menegazzo
I would suggest you to use str.formatinstead str %since its is "more modern" and also has a better set of features. That said what you want is:
我建议您str.format改用str %它，因为它“更现代”并且还具有更好的功能集。那就是说你想要的是：
>>> x = (1,2)
>>> y = 'hello'
>>> '{},{},{}'.format(*(x + (y,)))
1,2,hello
For all cool features of format(and some related to %as well) take a look at PyFormat.
对于所有很酷的功能format（以及一些与之相关的功能%），请查看PyFormat。
