Merge pull request #5275 from lindahua/dh/minmax2

Add minmax and extrema

base/abstractarray.jl

@@ -1675,6 +1675,35 @@ function maximum{T<:FloatingPoint}(A::AbstractArray{T})
     v
 end
 
+# extrema
+
+function extrema{T<:Real}(A::AbstractArray{T})
+    if isempty(A); error("argument must not be empty"); end
+    n = length(A)
+
+    # locate the first non NaN number
+    v = A[1]
+    i = 2
+    while v != v && i <= n
+        @inbounds v = A[i]
+        i += 1
+    end
+
+    vmin = v
+    vmax = v
+    while i <= n
+        @inbounds v = A[i]
+        if v > vmax
+            vmax = v
+        elseif v < vmin
+            vmin = v
+        end
+        i += 1
+    end
+
+    return (vmin, vmax)
+end
+
 
 ## map over arrays ##
 

base/exports.jl

@@ -489,6 +489,7 @@ export
     cumprod,
     cumsum,
     cumsum_kbn,
+    extrema,
     fill!,
     fill,
     find,
@@ -524,6 +525,7 @@ export
     maximum,
     min,
     minimum,
+    minmax,
     nans,
     ndims,
     nnz,

base/math.jl

@@ -10,7 +10,7 @@ export sin, cos, tan, sinh, cosh, tanh, asin, acos, atan,
        log, log2, log10, log1p, exponent, exp, exp2, exp10, expm1,
        cbrt, sqrt, erf, erfc, erfcx, erfi, dawson,
        ceil, floor, trunc, round, significand, 
-       lgamma, hypot, gamma, lfact, max, min, ldexp, frexp,
+       lgamma, hypot, gamma, lfact, max, min, minmax, ldexp, frexp,
        clamp, modf, ^, mod2pi,
        airy, airyai, airyprime, airyaiprime, airybi, airybiprime,
        besselj0, besselj1, besselj, bessely0, bessely1, bessely,
@@ -20,7 +20,7 @@ export sin, cos, tan, sinh, cosh, tanh, asin, acos, atan,
 
 import Base: log, exp, sin, cos, tan, sinh, cosh, tanh, asin,
              acos, atan, asinh, acosh, atanh, sqrt, log2, log10,
-             max, min, ceil, floor, trunc, round, ^, exp2, exp10
+             max, min, minmax, ceil, floor, trunc, round, ^, exp2, exp10
 
 import Core.Intrinsics.nan_dom_err
 
@@ -347,6 +347,10 @@ max{T<:FloatingPoint}(x::T, y::T) = ifelse((y > x) | (x != x), y, x)
 min{T<:FloatingPoint}(x::T, y::T) = ifelse((y < x) | (x != x), y, x)
 @vectorize_2arg Real min
 
+minmax{T<:FloatingPoint}(x::T, y::T) =  x <= y ? (x, y) :
+                                        x >  y ? (y, x) :
+                                        x == x ? (x, x) : (y, y)
+
 function exponent(x::Float64)
     if x==0 || !isfinite(x)
         throw(DomainError())

base/promotion.jl

@@ -181,6 +181,7 @@ cmp(x::Real, y::Real) = cmp(promote(x,y)...)
 
 max(x::Real, y::Real) = max(promote(x,y)...)
 min(x::Real, y::Real) = min(promote(x,y)...)
+minmax(x::Real, y::Real) = minmax(promote(x, y)...)
 
 ## catch-alls to prevent infinite recursion when definitions are missing ##
 
@@ -200,3 +201,5 @@ no_op_err(name, T) = error(name," not defined for ",T)
 
 max{T<:Real}(x::T, y::T) = ifelse(y < x, x, y)
 min{T<:Real}(x::T, y::T) = ifelse(x < y, x, y)
+minmax{T<:Real}(x::T, y::T) = x < y ? (x, y) : (y, x)
+

base/reduce.jl

@@ -48,6 +48,27 @@ function minimum(itr)
     return v
 end
 
+function extrema(itr)
+    s = start(itr)
+    if done(itr, s)
+        error("argument is empty")
+    end
+    (v, s) = next(itr, s)
+    vmin = v
+    vmax = v
+    while !done(itr, s)
+        (x, s) = next(itr, s)
+        if x == x
+            if x > vmax
+                vmax = x
+            elseif x < vmin
+                vmin = x
+            end
+        end
+    end
+    return (vmin, vmax)
+end
+
 function sum(itr)
     s = start(itr)
     if done(itr, s)

test/arrayops.jl

@@ -355,10 +355,15 @@ end
 
 @test maximum([4, 3, 5, 2]) == 5
 @test minimum([4, 3, 5, 2]) == 2
+@test extrema([4, 3, 5, 2]) == (2, 5)
+
 @test isnan(maximum([NaN]))
 @test isnan(minimum([NaN]))
+@test isequal(extrema([NaN]), (NaN, NaN))
+
 @test maximum([4., 3., NaN, 5., 2.]) == 5.
 @test minimum([4., 3., NaN, 5., 2.]) == 2.
+@test extrema([4., 3., NaN, 5., 2.]) == (2., 5.)
 
 @test any([true false; false false], 2) == [true false]'
 @test any([true false; false false], 1) == [true false]

test/numbers.jl

@@ -52,6 +52,13 @@
 @test 2. * 3. == 6.
 @test min(1.0,1) == 1
 
+@test minmax(5, 3) == (3, 5)
+@test minmax(3., 5.) == (3., 5.)
+@test minmax(5., 3.) == (3., 5.)
+@test minmax(3., NaN) == (3., 3.)
+@test minmax(NaN, 3.) == (3., 3.)
+@test isequal(minmax(NaN, NaN), (NaN, NaN))
+
 # lexing typemin(Int64)
 @test (-9223372036854775808)^1 == -9223372036854775808
 @test [1 -1 -9223372036854775808] == [1 -1 typemin(Int64)]