CODEWITHSUNDEEP
scalascala-2.10
akauppi
akauppi

Reputation: 18046

How to detect Infinity values in Scala?

Scala has Double.isNaN for detecting not-a-number but no Double.isInf for detecting (positive or negative) infinity.

Why? I'd like to check whether a parameter is a "real" number (i.e. has a numeric value). Converting it to a string and checking for "inf" or something will do it, but there must be a better way?

Like in C++: http://en.cppreference.com/w/cpp/numeric/math/isinf

Using Scala 2.10

Upvotes: 15

Views: 15890

Answers (3)

themel
themel

Reputation: 8895

What everyone else has said, plus this: the reason for the separate isNaN is that comparison with NaN is special: 

scala> val bar = Double.NaN
bar: Double = NaN

scala> bar == Double.NaN
res0: Boolean = false

No such rules apply for infinity, so there is no need for a special check function (except for the convenience of handling the sign):

scala> val foo: Double = Double.PositiveInfinity
foo: Double = Infinity

scala> foo == Double.PositiveInfinity
res1: Boolean = true

Upvotes: 4

Jens Egholm
Jens Egholm

Reputation: 2710

The method actually is there. It's just called isInfinity instead of isInf.

See scaladocs for RichDouble line 36: https://github.com/scala/scala/blob/v2.10.2/src/library/scala/runtime/RichDouble.scala#L36

Upvotes: 1

gourlaysama
gourlaysama

Reputation: 11280

Scala's Double has an isInfinite method, and Neg/Pos variants:

scala> val a = 22.0
a: Double = 22.0

scala> a.isInfinite
res0: Boolean = false

scala> val b = 2.0/0
b: Double = Infinity

scala> b.isInfinite
res1: Boolean = true

scala> b.isPosInfinity
res4: Boolean = true

Upvotes: 24

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