ruby on rails 如何处理 NaN
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ruby on rails how to deal with NaN
提问by Paul Phoenix
I have read few posts regarding NaNbut did not figure out how to deal with it in Ruby on Rails. I want to check a value if it is a NaNI want to replace it with Zero(0).
I tried the following
我读过几篇关于NaN但没有弄清楚如何在 Ruby on Rails 中处理它的帖子。我想检查一个值是否是一个NaN我想用零（0）替换它。我尝试了以下
logger.info(".is_a? Fixnum #{percent.is_a? Fixnum}")
when percent has NaNit returns me false.
当百分比有NaN它返回我错误。
I have made few changes in the logger
我在记录器中做了一些更改
logger.info("Fixnum #{percent.is_a? Fixnum} percent #{percent}")
Output
输出
Fixnum false percent 94.44444444444444
Fixnum false percent NaN
Fixnum false percent 87.0
回答by falsetru
NaNis instance of Float. Use Float#nan?method.
NaN是 的实例Float。使用Float#nan?方法。
>> nan = 0.0/0 # OR nan = Float::NAN
=> NaN
>> nan.class
=> Float
>> nan.nan?
=> true
>> nan.is_a?(Float) && nan.nan?
=> true
>> (nan.is_a?(Float) && nan.nan?) ? 0 : nan
=> 0
UPDATE
更新
NaNcould also be an instance of BigDecimal:
((nan.is_a?(Float) || nan.is_a?(BigDecimal)) && nan.nan?) ? 0 : nan
or
或者
{Float::NAN => 0, BigDecimal::NAN => 0}.fetch(nan, nan)
