Merge pull request #2 from tonyhffong/master

autoscale, suffix format options

Author: tonyhffong

README.md

@@ -198,5 +198,10 @@ The keyword arguments are (Bold keywards are not printf standard)
 * **fractionsep**. Default `/`
 * **fractionwidth**. Integer. Try to pad zeros to the numerator until the fractional part has this width
 * **tryden**. Integer. Try to use this denominator instead of a smaller one. No-op if it'd lose precision.
+* **suffix**. String. This strings will be appended to the output. Useful for units/%
+* **autoscale**. Symbol, default `:none`. It could be `:metric`, `:binary`, or `:finance`.
+    * `:metric` implements common SI symbols for large and small numbers e.g. `M`, `k`, `μ`, `n`
+    * `:binary` implements common ISQ symbols for large numbers e.g. `Ti`, `Gi`, `Mi`, `Ki`
+    * `:finance` implements common finance/news symbols for large numbers e.g. `b` (billion), `m` (millions)
 
 See the test script for more examples.

src/cformat.jl

@@ -98,7 +98,7 @@ end
 
 function generate_format_string(;
         width=nothing,
-        precision=nothing,
+        precision= -1,
         leftjustified=false,
         zeropadding=false,
         commas=false,
@@ -131,32 +131,35 @@ function generate_format_string(;
             s *= string( width )
         end
     end
-    if precision != nothing
+    if precision != -1
         s *= "." * string( precision )
     end
     s * conversion
 end
 
 function format{T<:Real}( x::T;
         width=nothing,
-        precision=nothing,
+        precision= -1,
         leftjustified::Bool=false,
         zeropadding::Bool=false, # when right-justified, use 0 instead of space to fill
         commas::Bool=false,
-        signed::Bool=false,
+        signed::Bool=false, # +/- prefix
         positivespace::Bool=false,
-        stripzeros::Bool=(precision==nothing),
+        stripzeros::Bool=(precision== -1),
         parens::Bool=false, # use (1.00) instead of -1.00. Used in finance
         alternative::Bool=false, # usually for hex
         mixedfraction::Bool=false,
         mixedfractionsep="_",
         fractionsep="/", # num / den
         fractionwidth::Int = 0,
         tryden = 0, # if 2 or higher, try to use this denominator, without losing precision
-        conversion::ASCIIString="")
+        suffix="", # useful for units/%
+        autoscale=:none, # :metric, :binary or :finance
+        conversion::ASCIIString=""
+        )
     checkwidth = commas
     if conversion == ""
-        if T <: FloatingPoint || T <: Rational && precision != nothing
+        if T <: FloatingPoint || T <: Rational && precision != -1
             actualconv = "f"
         elseif T <: Unsigned
             actualconv = "x"
@@ -175,6 +178,68 @@ function format{T<:Real}( x::T;
     if T <: Rational && conversion == "s"
         stripzeros = false
     end
+    if ( T <: FloatingPoint && actualconv == "f" || T <: Integer ) && autoscale != :none
+        actualconv = "f"
+        if autoscale == :metric
+            scales = [
+                (1e24, "Y" ),
+                (1e21, "Z" ),
+                (1e18, "E" ),
+                (1e15, "P" ),
+                (1e12, "T" ),
+                (1e9,  "G"),
+                (1e6,  "M"),
+                (1e3,  "k") ]
+            if abs(x) > 1
+                for (mag, sym) in scales
+                    if abs(x) >= mag
+                        x /= mag
+                        suffix = sym * suffix
+                        break
+                    end
+                end
+            elseif T <: FloatingPoint
+                smallscales = [
+                    ( 1e-12, "p" ),
+                    ( 1e-9,  "n" ),
+                    ( 1e-6,  "μ" ),
+                    ( 1e-3,  "m" ) ]
+                for (mag,sym) in smallscales
+                    if abs(x) < mag*10
+                        x /= mag
+                        suffix = sym * suffix
+                        break
+                    end
+                end
+            end
+        else
+            if autoscale == :binary
+                scales = [
+                    (1024.0 ^8,  "Yi" ),
+                    (1024.0 ^7,  "Zi" ),
+                    (1024.0 ^6,  "Ei" ),
+                    (1024^5,  "Pi" ),
+                    (1024^4,  "Ti" ),
+                    (1024^3,  "Gi"),
+                    (1024^2,  "Mi"),
+                    (1024,    "Ki")
+                ]
+            else # :finance
+                scales = [
+                    (1e12, "t" ),
+                    (1e9,  "b"),
+                    (1e6,  "m"),
+                    (1e3,  "k") ]
+            end
+            for (mag, sym) in scales
+                if abs(x) >= mag
+                    x /= mag
+                    suffix = sym * suffix
+                    break
+                end
+            end
+        end
+    end
 
     nonneg = x >= 0
     fractional = 0
@@ -264,6 +329,8 @@ function format{T<:Real}( x::T;
         end
     end
 
+    s *= suffix
+
     if parens && !in( actualconv[1], "xX" )
         # if zero or positive, we still need 1 white space on the right
         if nonneg

test/cformat.jl

@@ -156,6 +156,26 @@ function test_format()
     # same with unspecified width
     @test format(  12345678, commas=true, parens=true )== " 12,345,678 "
     @test format( -12345678, commas=true, parens=true )== "(12,345,678)"
+
+    @test format( 1.2e9, autoscale = :metric ) == "1.2G"
+    @test format( 1.2e6, autoscale = :metric ) == "1.2M"
+    @test format( 1.2e3, autoscale = :metric ) == "1.2k"
+    @test format( 1.2e-6, autoscale = :metric ) == "1.2μ"
+    @test format( 1.2e-9, autoscale = :metric ) == "1.2n"
+    @test format( 1.2e-12, autoscale = :metric ) == "1.2p"
+
+    @test format( 1.2e9, autoscale = :finance ) == "1.2b"
+    @test format( 1.2e6, autoscale = :finance ) == "1.2m"
+    @test format( 1.2e3, autoscale = :finance ) == "1.2k"
+
+    @test format( 0x40000000, autoscale = :binary ) == "1Gi"
+    @test format( 0x100000, autoscale = :binary ) == "1Mi"
+    @test format( 0x800, autoscale = :binary ) == "2Ki"
+    @test format( 0x400, autoscale = :binary ) == "1Ki"
+
+    @test format( 100.00, precision=2, suffix="%" ) == "100.00%"
+    @test format( 100, precision=2, suffix="%" ) == "100%"
+    @test format( 100, precision=2, suffix="%", conversion="f" ) == "100.00%"
 end
 
 test_commas()