blocks|key|431875|text|这是可行的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|431876|from+math+import+trunc
some_float+=+1234.5678

print+'{:d}'.format(trunc(some_float))
=>+1234|code-block|syntax|javascript|431877|或者干脆这样做：|431878|print+trunc(some_float)
=>+1234|431879|我认为这是一个可以接受的答案，它避免了向int的转换。请注意，在这段代码中：'%2502d'+%25+some_float正在进行到int的隐式转换，您无法避免某种类型的转换，以便以所需的格式打印。|offset|length|style|CODE|431880|entityMap^0|0|0|0|0|K|3|12|J|1Q|3|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@$M|X|N|Y|O|P]|$M|Z|N|10|O|P]|$M|11|N|12|O|P]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|R|$]]

This works:

<pre><code>from math import trunc
some_float = 1234.5678

print '{:d}'.format(trunc(some_float))
=&gt; 1234
</code></pre>

Or just do this, for that matter:

<pre><code>print trunc(some_float)
=&gt; 1234
</code></pre>

I think it's an acceptable answer, it avoids the conversion to <code>int</code>. Notice that in this snippet: <code>'%02d' % some_float</code> an implicit conversion to <code>int</code> is happening, you can't avoid some sort of conversion for printing in the desired format.

blocks|key|213567|text|可以通过扩展类string.Formatter来扩展标准字符串格式化语言|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|213568|class+MyFormatter(Formatter):
++++def+format_field(self,+value,+format_spec):
++++++++if+format_spec+==+'t':++#+Truncate+and+render+as+int
++++++++++++return+str(int(value))
++++++++return+super(MyFormatter,+self).format_field(value,+format_spec)

MyFormatter().format("{0}+{1:t}",+"Hello",+4.567)++#+returns+"Hello+4"|code-block|syntax|javascript|213569|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/2/library/string.html#string.Formatter^0|7|G|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

It's possible to extend the standard string formatting language by extending the class <a href="http://docs.python.org/2/library/string.html#string.Formatter">string.Formatter</a>:

<pre><code>class MyFormatter(Formatter):
 def format_field(self, value, format_spec):
 if format_spec == 't': # Truncate and render as int
 return str(int(value))
 return super(MyFormatter, self).format_field(value, format_spec)

MyFormatter().format("{0} {1:t}", "Hello", 4.567) # returns "Hello 4"
</code></pre>

blocks|key|431954|text|这也是可行的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|431955|some_float+=+1234.5678
f+=+lambda+x:+str(x)[:str(x).find('.')]
print+'{}'.format(f(some_float))
=>+1234|code-block|syntax|javascript|431956|在做了%25timeit测试之后，它看起来比trunc方法要快一点。|431957|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

This will work too:

<pre><code>some_float = 1234.5678
f = lambda x: str(x)[:str(x).find('.')]
print '{}'.format(f(some_float))
=&gt; 1234
</code></pre>

After doing a %timeit test it looks like this is a bit faster than the trunc method.

blocks|key|213699|text|值得一提的是，关于如何使用原始格式字符串呈现浮点数的内置行为。如果您事先知道小数部分相对于0.5的位置，您可以利用最初尝试的格式字符串，但发现它不符合舍入副作用"{:0.0f}"。看看下面的例子。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|213700|>>>+"{:0.0f}".format(1.999)
'2'
>>>+"{:0.0f}".format(1.53)
'2'
>>>+"{:0.0f}".format(1.500)
'2'
>>>+"{:0.0f}".format(1.33)
'1'
>>>+"{:0.0f}".format(0.501)
'1'
>>>+"{:0.0f}".format(0.5)
'0'
>>>+"{:0.0f}".format(0.1)
'0'
>>>+"{:0.0f}".format(0.001)
'0'|code-block|syntax|javascript|213701|正如您所看到的，在幕后有舍入行为。在我的例子中，我有一个将整数转换为浮点数的数据库，我知道我提前处理的是一个非小数部分，只想在html模板中呈现浮点数的int部分作为变通办法。当然，如果您事先不知道小数部分，则需要首先对浮点数执行某种截断操作。|213702|entityMap^0|28|9|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

It's worth mentioning the built in behavior for how floats are rendered using the raw format strings. If you know in advance where your fractional part lies with respect to 0.5 you can leverage the format string you originally attempted but discovered it fell short from rounding side effects <code>"{:0.0f}"</code>. Check out the following examples...

<pre><code>&gt;&gt;&gt; "{:0.0f}".format(1.999)
'2'
&gt;&gt;&gt; "{:0.0f}".format(1.53)
'2'
&gt;&gt;&gt; "{:0.0f}".format(1.500)
'2'
&gt;&gt;&gt; "{:0.0f}".format(1.33)
'1'
&gt;&gt;&gt; "{:0.0f}".format(0.501)
'1'
&gt;&gt;&gt; "{:0.0f}".format(0.5)
'0'
&gt;&gt;&gt; "{:0.0f}".format(0.1)
'0'
&gt;&gt;&gt; "{:0.0f}".format(0.001)
'0'
</code></pre>

As you can see there's rounding behavior behind the scenes. In my case where I had a database converting ints to floats I knew I was dealing with a non fractional part in advance and only wanted to render in an html template the int portion of the float as a workaround. Of course if you don't know in advance the fractional part you would need to carry out a truncation operation of some sort first on the float.

A quick no-brainer:

<pre><code>some_float = 1234.5678
print '%02d' % some_float # 1234

some_float = 1234.5678
print '{WHAT?}'.format(some_float) # I want 1234 here too
</code></pre>

Note: <code>{:.0f}</code> is not an option, because it rounds (returns <code>1235</code> in this example).

<code>format(..., int(some_float))</code> is exactly the thing I'm trying to avoid, please don't suggest that.

Format truncated Python float as int in string

数据库

一句简单的话：some_float = 1234.5678print '%02d' % some_float  # 1234some_float = 1234.5678print '{WHAT?}'.format(some_float) # I want 1234 here too注意：{:.0f}不是一个选项，因为它...

问将截断的Python浮点数格式化为字符串中的整型
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