将Python字符串格式化与列表一起使用

问题:将Python字符串格式化与列表一起使用

s在Python 2.6.5中构造了一个字符串,该字符串将具有不同数量的%s令牌,这些令牌与list中的条目数匹配x。我需要写出格式化的字符串。以下内容不起作用,但表示我要执行的操作。在此示例中,有三个%s标记,并且列表具有三个条目。

s = '%s BLAH %s FOO %s BAR'
x = ['1', '2', '3']
print s % (x)

我希望输出字符串为:

1 BLAH 2 FOO 3 BAR

I construct a string s in Python 2.6.5 which will have a varying number of %s tokens, which match the number of entries in list x. I need to write out a formatted string. The following doesn’t work, but indicates what I’m trying to do. In this example, there are three %s tokens and the list has three entries.

s = '%s BLAH %s FOO %s BAR'
x = ['1', '2', '3']
print s % (x)

I’d like the output string to be:

1 BLAH 2 FOO 3 BAR


回答 0

print s % tuple(x)

代替

print s % (x)
print s % tuple(x)

instead of

print s % (x)

回答 1

您应该看一下python 的format方法。然后,您可以像这样定义格式字符串:

>>> s = '{0} BLAH BLAH {1} BLAH {2} BLAH BLIH BLEH'
>>> x = ['1', '2', '3']
>>> print s.format(*x)
'1 BLAH BLAH 2 BLAH 3 BLAH BLIH BLEH'

You should take a look to the format method of python. You could then define your formatting string like this :

>>> s = '{0} BLAH BLAH {1} BLAH {2} BLAH BLIH BLEH'
>>> x = ['1', '2', '3']
>>> print s.format(*x)
'1 BLAH BLAH 2 BLAH 3 BLAH BLIH BLEH'

回答 2

在此资源页面之后,如果x的长度变化,我们可以使用:

', '.join(['%.2f']*len(x))

为列表中的每个元素创建一个占位符x。这是示例:

x = [1/3.0, 1/6.0, 0.678]
s = ("elements in the list are ["+', '.join(['%.2f']*len(x))+"]") % tuple(x)
print s
>>> elements in the list are [0.33, 0.17, 0.68]

Following this resource page, if the length of x is varying, we can use:

', '.join(['%.2f']*len(x))

to create a place holder for each element from the list x. Here is the example:

x = [1/3.0, 1/6.0, 0.678]
s = ("elements in the list are ["+', '.join(['%.2f']*len(x))+"]") % tuple(x)
print s
>>> elements in the list are [0.33, 0.17, 0.68]

回答 3

这是一行代码。一个临时的答案,使用带有print()的format来迭代列表。

怎么样(Python 3.x):

sample_list = ['cat', 'dog', 'bunny', 'pig']
print("Your list of animals are: {}, {}, {} and {}".format(*sample_list))

在此处阅读有关使用format()的文档。

Here is a one liner. A little improvised answer using format with print() to iterate a list.

How about this (python 3.x):

sample_list = ['cat', 'dog', 'bunny', 'pig']
print("Your list of animals are: {}, {}, {} and {}".format(*sample_list))

Read the docs here on using format().


回答 4

由于我刚刚学到了这个很酷的东西(从格式字符串中索引到列表中),所以我添加了这个老问题。

s = '{x[0]} BLAH {x[1]} FOO {x[2]} BAR'
x = ['1', '2', '3']
print (s.format (x=x))

输出:

1 BLAH 2 FOO 3 BAR

但是,我仍然没有弄清楚如何进行切片(在格式字符串'"{x[2:4]}".format...中),并且很想弄清楚是否有人有想法,但是我怀疑您根本无法做到这一点。

Since I just learned about this cool thing(indexing into lists from within a format string) I’m adding to this old question.

s = '{x[0]} BLAH {x[1]} FOO {x[2]} BAR'
x = ['1', '2', '3']
print (s.format (x=x))

Output:

1 BLAH 2 FOO 3 BAR

However, I still haven’t figured out how to do slicing(inside of the format string '"{x[2:4]}".format...,) and would love to figure it out if anyone has an idea, however I suspect that you simply cannot do that.


回答 5

这是一个有趣的问题!处理可变长度列表的另一种方法是构建一个充分利用该.format方法和列表拆包的功能。在下面的示例中,我不使用任何特殊的格式,但是可以轻松地对其进行更改以满足您的需求。

list_1 = [1,2,3,4,5,6]
list_2 = [1,2,3,4,5,6,7,8]

# Create a function that can apply formatting to lists of any length:
def ListToFormattedString(alist):
    # Create a format spec for each item in the input `alist`.
    # E.g., each item will be right-adjusted, field width=3.
    format_list = ['{:>3}' for item in alist] 

    # Now join the format specs into a single string:
    # E.g., '{:>3}, {:>3}, {:>3}' if the input list has 3 items.
    s = ','.join(format_list)

    # Now unpack the input list `alist` into the format string. Done!
    return s.format(*alist)

# Example output:
>>>ListToFormattedString(list_1)
'  1,  2,  3,  4,  5,  6'
>>>ListToFormattedString(list_2)
'  1,  2,  3,  4,  5,  6,  7,  8'

This was a fun question! Another way to handle this for variable length lists is to build a function that takes full advantage of the .format method and list unpacking. In the following example I don’t use any fancy formatting, but that can easily be changed to suit your needs.

list_1 = [1,2,3,4,5,6]
list_2 = [1,2,3,4,5,6,7,8]

# Create a function that can apply formatting to lists of any length:
def ListToFormattedString(alist):
    # Create a format spec for each item in the input `alist`.
    # E.g., each item will be right-adjusted, field width=3.
    format_list = ['{:>3}' for item in alist] 

    # Now join the format specs into a single string:
    # E.g., '{:>3}, {:>3}, {:>3}' if the input list has 3 items.
    s = ','.join(format_list)

    # Now unpack the input list `alist` into the format string. Done!
    return s.format(*alist)

# Example output:
>>>ListToFormattedString(list_1)
'  1,  2,  3,  4,  5,  6'
>>>ListToFormattedString(list_2)
'  1,  2,  3,  4,  5,  6,  7,  8'

回答 6

与@neobot的答案相同,但更加现代和简洁。

>>> l = range(5)
>>> " & ".join(["{}"]*len(l)).format(*l)
'0 & 1 & 2 & 3 & 4'

The same as @neobot’s answer but a little more modern and succinct.

>>> l = range(5)
>>> " & ".join(["{}"]*len(l)).format(*l)
'0 & 1 & 2 & 3 & 4'

回答 7

x = ['1', '2', '3']
s = f"{x[0]} BLAH {x[1]} FOO {x[2]} BAR"
print(s)

输出是

1 BLAH 2 FOO 3 BAR
x = ['1', '2', '3']
s = f"{x[0]} BLAH {x[1]} FOO {x[2]} BAR"
print(s)

The output is

1 BLAH 2 FOO 3 BAR