Question

I am puzzled why I can assign/unpack the return of split() to the appropriate number of variables, but the same fails for use in a print string using formatting directives.

例如,考虑到:

In [202]: s
Out[202]:  here are 4 values 

In [203]: s.split()
Out[203]: [ here ,  are ,  4 ,  values ]

这项工程按预期进行:

In [204]: a, b, c, d = s.split()

In [205]: print  %s %s %s %s  % (a, b, c, d)
here are 4 values

但这失败了。

 In [206]: print  %s %s %s %s  % (s.split())

I am not sure why? Shouldn t the return of split() be unpacked and be distributed over the expected arguments for the formatting strings?

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
C:laDesktop<ipython-input-206-600f130ff0b2> in <module>()
----> 1 print  %s %s %s %s  % (s.split())

TypeError: not enough arguments for format string

“说明有足够的论据”。我确实有名单上的项目数目。由于某种原因,该清单是否没有包装,而是没有转让变数?

I came across this in attempting to answer this question writing column entry just one below another in python

Answer 1

页: 1

>>> s =  here are 4 values 
>>>  %s %s %s %s  % tuple(s.split())
 here are 4 values

http://docs.python.org/library/string.html#format-string-syntax” rel=“nofollow”>code>.format(, 相反,没有包装这些论点。

 {0} {1} {2} {3} .format(*s.split())

Answer 2

The fundamental problem is that %-formatting and unpacking aren t related at all. The % requires that the values be in a tuple; other kinds of sequences won t work. (It will accept a single non-tuple value though.)

这产生了不幸的后果,即所有标记都被视为价值之 t,无论是否可取。 a. 治疗 a 价值是,你必须用另一图:

>>>  %s  % ( a ,  b )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: not all arguments converted during string formatting
>>>  %s  % (( a ,  b ),)
"( a ,  b )"

使用<条码>格式更为可取。

Answer 3

我认为,问题在于,有 %的字塔允许提出不包装的论点。这里使用的方法是:

>>> s =  Here are some values 
>>>  {} {} {} {} .format(*s.split())
 Here are some values

@senderle指出,这一辛迪加只为第2.7页而工作,因此,这里的编码将与以前的版本合作:

>>> s =  Here are some values 
>>>  {0} {1} {2} {3} .format(*s.split())
 Here are some values

Answer 4

>>> s =  here are 4 values 
>>> print  %s %s %s %s  % tuple(s.split())
here are 4 values
>>> print  %s  % s.split()
[ here ,  are ,  4 ,  values ]

灰色正试图改变名单,以扼杀它只需要1个参数。

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