Is there an equivalent of MATLAB's Workspace window in Mathematica?

Question

For example, in MATLAB, a panel is available where one can see straightaway which variables are used and their dimension sizes. Is such a feature available in Mathematica? I really find it hard to scroll up and down to see where things are in Mathematica; I just want to see at a glance what's been used.

Answer 1

Below is something posted on Mathgroup by Jason McKenzie Alexander. I made a few tiny changes and corresponded about this with Jason for a short while. He sent me his final version, which I post here with his permission. The original (linked above) is really only a few lines of code and can be studied to grasp the principle. The code below is a full package.

BeginPackage["Inspector`"]

StateInspector::usage="Create a dynamic state inspector for the Global` context.";

StateInspectorViewer::usage="Show a dynamic state inspector for the Global` context.";

Begin["`Private`"]

AddNewSymbolHook[]:=$NewSymbol=(If[#2=="Global`",
(#1=#2)&[Symbol["Inspector`Variables`"<>#1],False];
(#1=#2)&[Symbol["Inspector`Variables`"<>#1<>"`up"],True];
(*
Much of the time the OwnValues of a symbol isn't interesting,
so the default on whether to show it is False.
*)
(#1=#2)&[Symbol["Inspector`Variables`"<>#1<>"`own"],False];
(#1=#2)&[Symbol["Inspector`Variables`"<>#1<>"`down"],True];
]&);

UpValuesQ[s_String]:=If[ToExpression[s,StandardForm,UpValues]=!={},True,False]
OwnValuesQ[s_String]:=If[ToExpression[s,StandardForm,OwnValues]=!={},True,False]
DownValuesQ[s_String]:=If[ToExpression[s,StandardForm,DownValues]=!={},True,False]

MakeUpValueView[s_String]:=
If[UpValuesQ[s]===False,
ToClobberNull,
OpenerView[
{
"UpValues",
Framed[Dynamic[ToExpression[s,StandardForm,UpValues]],
ImageSize->Scaled[1],Background->White]
},
ToExpression["Dynamic[Inspector`Variables`"<>s<>"`up]"]
]
]

MakeOwnValueView[s_String]:=
If[OwnValuesQ[s]===False,
ToClobberNull,
OpenerView[
{
"OwnValues",
Framed[Dynamic[ToExpression[s,StandardForm,OwnValues]],
ImageSize->Scaled[1],Background->White]
},
ToExpression["Dynamic[Inspector`Variables`"<>s<>"`own]"]
]
]

MakeDownValueView[s_String]:=
If[DownValuesQ[s]===False,
ToClobberNull,
OpenerView[
{
"DownValues",
Framed[Dynamic[ToExpression[s,StandardForm,DownValues]],
ImageSize->Scaled[1],Background->White]
},
ToExpression["Dynamic[Inspector`Variables`"<>s<>"`down]"]
]
]

ConstructColumn[s_String]:=If[
UpValuesQ[s]===False&&OwnValuesQ[s]===False&&DownValuesQ[s]===False,
Framed[Dynamic[Symbol[s]],ImageSize->Scaled[1],Background->White],
Column[
DeleteCases[
{
Framed[Dynamic[Symbol[s]],ImageSize->Scaled[1],Background->White],
MakeUpValueView[s],
MakeOwnValueView[s],
MakeDownValueView[s]
},ToClobberNull
]
]
]

StateInspector[]:=(AddNewSymbolHook[];StateInspector["Global`"])

StateInspector[s_String]:=(AddNewSymbolHook[];Dynamic@Refresh[
Grid[
Partition[
(OpenerView[
{
Row[{
Style[#,FontFamily->"Arial"],
Spacer[6],
Button[Style["Clear",10],ToExpression["Clear["<>#<>"]"],Appearance->"Palette"],
Spacer[6],
Button[Style["Remove",10],
ToExpression["Remove["<>#<>","
<>"Inspector`Variables`"<>#<>","
<>"Inspector`Variables`"<>#<>"`up,"
<>"Inspector`Variables`"<>#<>"`own,"
<>"Inspector`Variables`"<>#<>"`down]"],
Appearance->"Palette"
],
(*Button[Style["Remove",10],ToExpression["Remove["<>#<>"]"],Appearance->"Palette"]*)
}],
Inspector`Private`ConstructColumn[#]
},ToExpression["Dynamic[Inspector`Variables`"<>#<>"]"]
]&)/@Names[s<>"*"],3,3,{1,1},{}
],
Alignment->{Left,Baseline},Background->{Automatic,{{RGBColor[0.98996, 0.950057, 0.785382],RGBColor[1, 0.983169, 0.877287]}}},
ItemSize->Scaled[.333]
],
UpdateInterval->1
])

StateInspectorViewer[]:=(AddNewSymbolHook[];StateInspectorViewer["Global`"])

StateInspectorViewer[s_String]:=(AddNewSymbolHook[];CreateDocument@Pane@Column[{
Row[{
Style["Mathematica",Italic,"Title"],
Style[" state inspector","Title"]
}],
Row[{
Style["Context: ","Subtitle"],
Spacer[6],
Style[s,"Subtitle",FontFamily->"Courier"]
}],
Spacer[6],
StateInspector[s]
}])

End[]

EndPackage[]

Answer 2

An ugly hack, look at all things in Global context, keep in table if Dimensions didn't return {}

Grid[Select[{#, Dimensions[ToExpression@#]} & /@ 
   Names["Global`*"], #[[2]] != {} &], Alignment -> Left]

For this to be helpful it needs to be updated dynamically and preferably be in a palette to avoid scrolling up all the time. Instead of displaying just lists this displays everything other than those with Head Symbol. It also shows the Head for all variables, for numbers it shows the value, for lists the dimension and for strings the length.

CreateWindow@PaletteNotebook@Dynamic[Grid[
    Select[
     With[{expr = ToExpression@#},
        {#,
         Head[expr],
         Which[
          ListQ[expr], Dimensions[expr],
          NumericQ[expr], expr,
          StringQ[expr], StringLength[expr],
          True, "-"]}] & /@ Names["Global`*"],
     (#[[2]] =!= Symbol) &],
    Alignment -> Left],
    UpdateInterval -> 10, TrackedSymbols->{}]

Or you could have it update only when clicking a button:

CreateWindow@
 PaletteNotebook[{Button["Refresh", 
    vars = Framed[
      Grid[Select[With[{expr = ToExpression@#}, {#, Head[expr],
            Which[
             ListQ[expr], Dimensions[expr],
             NumericQ[expr], expr,
             StringQ[expr], StringLength[expr],
             True, "-"]}] & /@ 
         Names["Global`*"], (#[[2]] =!= Symbol) &], 
       Alignment -> Left], FrameStyle -> None, FrameMargins -> 5]],
   Dynamic[vars]},
  WindowElements -> {"VerticalScrollBar"},
  WindowTitle -> "Global`*"]

EDIT: In a palette and dynamic, thanks acl.

Answer 3

You could do this:

Names["Global`*"]

It looks for symbols in the Global context which is where "global variables" are defined. The * is a wildcart which you can modify to narrow down the search. Look at the docs for Names.