Skip to main content

plotting - Extracting data values from a plot


I found that the fact is very useful that a plot sometimes contains all the original data needed to reconstruct that plot. This is very helpful for me because sometimes I need to retrieve and analysis the numerical data in plots I produced in the past. It's much easier for me(in the sense of organization of projects) to just save the plots in notebooks rather than save the numerical data in some separated files.


For example:


data1 = {{1., 2.}, {2., 3.}, {3., 1.}};
pic1 = ListPlot[data1, Joined -> True]

enter image description here


I can get the data back using


Cases[pic1, Line[x__] -> x, ∞]

(* {{{1., 2.}, {2., 3.}, {3., 1.}}} *)

This works great most of the time, but sometimes when I specified a plot range, some data are lost:


data2 = Table[{x, Cos[x]^2}, {x, -π/2, π/2, π/8}] // N;
ListPlot[data2, Joined -> True]
pic2 = ListPlot[data2, PlotRange -> {{0, 1.5}, {0, 0.5}}, Joined -> True]

enter image description here enter image description here


Graphics[Cases[pic2, _Line, ∞], AspectRatio -> 1/GoldenRatio, Axes -> True]


enter image description here


Note that the data are lost only at the vertical direction. So are there ways to tell Mathematica to save all the data into the plot?



Answer



Use Show to impose PlotRange:


data2 = Table[{x, Cos[x]^2}, {x, -π/2, π/2, π/8}];
ListPlot[data2, Joined -> True]
pic2 = Show[ListPlot[data2, Joined -> True], PlotRange -> {{0, 1.5}, {0, 0.5}}]

Then this will give you everything:


Graphics[Cases[pic2, _Line, ∞], AspectRatio -> 1/GoldenRatio, Axes -> True]

Comments

Post a Comment

Popular posts from this blog

functions - Get leading series expansion term?

Given a function f[x] , I would like to have a function leadingSeries that returns just the leading term in the series around x=0 . For example: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x)] x and leadingSeries[(1/x + 2 + (1 - 1/x^3)/4)/(4 + x)] -(1/(16 x^3)) Is there such a function in Mathematica? Or maybe one can implement it efficiently? EDIT I finally went with the following implementation, based on Carl Woll 's answer: lds[ex_,x_]:=( (ex/.x->(x+O[x]^2))/.SeriesData[U_,Z_,L_List,Mi_,Ma_,De_]:>SeriesData[U,Z,{L[[1]]},Mi,Mi+1,De]//Quiet//Normal) The advantage is, that this one also properly works with functions whose leading term is a constant: lds[Exp[x],x] 1 Answer Update 1 Updated to eliminate SeriesData and to not return additional terms Perhaps you could use: leadingSeries[expr_, x_] := Normal[expr /. x->(x+O[x]^2) /. a_List :> Take[a, 1]] Then for your examples: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x), x] leadingSeries[Exp[x], x] leadingSeries[(1/x + 2 + (1 - 1/x...
Post a Comment
Read more

How to thread a list

I have data in format data = {{a1, a2}, {b1, b2}, {c1, c2}, {d1, d2}} Tableform: I want to thread it to : tdata = {{{a1, b1}, {a2, b2}}, {{a1, c1}, {a2, c2}}, {{a1, d1}, {a2, d2}}} Tableform: And I would like to do better then pseudofunction[n_] := Transpose[{data2[[1]], data2[[n]]}]; SetAttributes[pseudofunction, Listable]; Range[2, 4] // pseudofunction Here is my benchmark data, where data3 is normal sample of real data. data3 = Drop[ExcelWorkBook[[Column1 ;; Column4]], None, 1]; data2 = {a #, b #, c #, d #} & /@ Range[1, 10^5]; data = RandomReal[{0, 1}, {10^6, 4}]; Here is my benchmark code kptnw[list_] := Transpose[{Table[First@#, {Length@# - 1}], Rest@#}, {3, 1, 2}] &@list kptnw2[list_] := Transpose[{ConstantArray[First@#, Length@# - 1], Rest@#}, {3, 1, 2}] &@list OleksandrR[list_] := Flatten[Outer[List, List@First[list], Rest[list], 1], {{2}, {1, 4}}] paradox2[list_] := Partition[Riffle[list[[1]], #], 2] & /@ Drop[list, 1] RM[list_] := FoldList[Transpose[{First@li...
Post a Comment
Read more

front end - keyboard shortcut to invoke Insert new matrix

I frequently need to type in some matrices, and the menu command Insert > Table/Matrix > New... allows matrices with lines drawn between columns and rows, which is very helpful. I would like to make a keyboard shortcut for it, but cannot find the relevant frontend token command (4209405) for it. Since the FullForm[] and InputForm[] of matrices with lines drawn between rows and columns is the same as those without lines, it's hard to do this via 3rd party system-wide text expanders (e.g. autohotkey or atext on mac). How does one assign a keyboard shortcut for the menu item Insert > Table/Matrix > New... , preferably using only mathematica? Thanks! Answer In the MenuSetup.tr (for linux located in the $InstallationDirectory/SystemFiles/FrontEnd/TextResources/X/ directory), I changed the line MenuItem["&New...", "CreateGridBoxDialog"] to read MenuItem["&New...", "CreateGridBoxDialog", MenuKey["m", Modifiers-...
Post a Comment
Read more