Finding duplicates

Question

People often ask me*, "Kuba how come you can so quickly find duplicates? It appears tough in this syntax rich environment."

If a question feels like a duplicate or a one that is already answered, it probably is. Here is how you can speed up searching for a duplicate:**

• Efficient querying with SE search engine and other general rules

• Index of 'There is a function exactly for that' answers

• Index of characteristic syntax lookup

(*) no they don't but they should! :)

(**) feel free to contribute to that topic

Answer 1

Very often the answer is obvious but good luck finding list[[##]]& @@ {1,2,5} or Table[With[{i = i}, .... I keep that list of bookmarks as well.

This list is slightly subjective because the piece of code is what I think characterizes the answer or the problem best. In case of answers it does not need to be the best answer but probably the most idiomatic one in WL.

Once you know it is here you can just Ctrl+F and find a characteristic piece of syntax:

syntax

• list[[1]][[2]] = 3 error

• foo @@ list

• foo @@@ list (could be better)

• list[[;; ;; n]]; or Span

functional-style

• list[[##]]& @@ {1,2}

• {##, foo[##]} & @@@ list

function-construction variables

• foo[x___]:=

• ToExpression["x"] = 5

replacement pattern-matching comparison

• expr /. a/b -> c

• Use :> not ->

• Use === not ==

• Use Alternatives | not Or ||

• {(_foo|_bar)..}

• Cases levelspec is {1} not {0}

dynamic manipulate gui-construction

• foo[x_]:=x a ; Manipulate[foo[x], {a,}]

• Dynamic[4] / 2

• Dynamic[update; ..., TrackedSymbols:>{update}]

• Don't forget TrackedSymbols:>{} when UpdateInterval is set.

• Method->"Queued" for Button+ MessageDialog

list-manipulation

• {{5, 4}, {5, 2}, {5, 1}} - {2, 2}

• {foo, bar} + {{a,b},{c,d}} ---> {{foo[a], bar[b]}, {foo[c], bar[d]}}

• foo + {1,2,3,4} ---> {1, f[2, 3], 4}

• {#[[1, 1]], #[[;; , 2]]}& /@ GatherBy[list, First]

• MatrixForm[array] // Dimensions

plotting

• ContourPlot3D quality, MaxRecursion or Plot3D

• ListPlot @ Transpose @ {xx, yy}

• Show only takes options from the first arg

other-tags

• With[{i=i},...

• Import /@ FileNames["*.jpg"]

• Table @ Export @ ToString @ i with StringJoin/StringTemplate

• Just ClearAll before solving

• "s" <> Style["s", Red]

tbc...

Answer 2

1. Aim for the answer.

   There is no point in looking for a question duplicate as opposed to looking for an answer that fits and was posted before. If I don't know if it exists or I don't remember keywords that would help me to locate it do e.g.:

   is:a [list-manipulation] [filtering] +keywords specific to the most obvious answer to that question

   Assuming the question was related to selecting form list.

   Additionally you can play with isaccepted:yes and [faq] if you are confident about the answer being the accepted one or that this is really a FAQ question.

2. I often do but don't forget about

   What are the most common pitfalls awaiting new users?

   many FAQs are answered there.

tbc..

Answer 3

Sometimes the answer is built-in, it must have been asked/answered before. But good luck with finding the answer "Transpose" among many answers that use it.

'There is a function exactly for that'

I keep that list in my browser bookmarks but I decided to move it here:

list-manipulation

• MapThread

• NestList

• SortBy

• Table NOT For (a) (b)

• Tally

• Transpose

• Reverse[_, 2]

plotting

• ContourPlot for implicit equations

• Show 2D case

• Show 3D case

other-tags

• Chop

• Save DumpSave Put

Or there is an option for that:

• AspectRatio -> Automatic

• Axes -> False

• SaveDefinitions -> True

tbc...