chart: show top 10 (or --items N) accounts, sorted by amount

Commands/Chart.hs

@@ -23,6 +23,7 @@ import Data.Colour.RGBSpace
 import Data.Colour.RGBSpace.HSL (hsl)
 import Data.Colour.SRGB.Linear (rgb)
 import Data.List
+import Safe (readDef)
 
 -- | Generate an image with the pie chart and write it to a file
 chart :: [Opt] -> [String] -> Ledger -> IO ()
@@ -56,9 +57,13 @@ genPie opts filterspec l = defaultPieLayout
     where
       pie_chart = defaultPieChart { pie_data_ = items, pie_colors_ = mkColours}
       items = mapMaybe (uncurry accountPieItem) $
-              flatten $
+              top num $
               balances $
               ledgerAccountTree (fromMaybe 99999 $ depthFromOpts opts) $ cacheLedger'' filterspec l
+      top n t = topn ++ [other]
+          where (topn,rest) = splitAt n $ reverse $ sortBy (comparing snd) $ flatten t
+                other = ("other", sum $ map snd rest)
+      num = readDef 10 (getOption opts ChartItems "10")
 
 -- | Convert all quantities of MixedAccount to a single commodity
 amountValue :: MixedAmount -> Double

Options.hs

@@ -86,6 +86,7 @@ options = [
  ,Option ""    ["debug-no-ui"]  (NoArg  DebugNoUI)     "run ui commands with no output"
 #ifdef CHART
  ,Option "o" ["output"]  (ReqArg ChartOutput "FILE")    "chart: output filename (default: hledger.png)"
+ ,Option ""  ["items"]  (ReqArg ChartItems "N")     "chart: number of accounts to show (default: 10)"
  ,Option ""  ["size"] (ReqArg ChartSize "WIDTHxHEIGHT") "chart: image size (default: 1024x1024)"
 #endif
  ]
@@ -118,6 +119,7 @@ data Opt =
     | DebugNoUI
 #ifdef CHART
     | ChartOutput {value::String}
+    | ChartItems  {value::String}
     | ChartSize   {value::String}
 #endif
     deriving (Show,Eq)