Computing lists using AstronomicalData

Question

Edit:

Initially in my question I asked how I could search the database of AstronomicalData["Exoplanets"] and return 2 filtered values that only contained valued cases, which would be placed into a ListLogPlot. The necessity was to achieve 3 lists that had 2 sets of data, however my method required having to manually copy the results into their lists that didn't contain _Missing data.

The lists required categorization of the radii of exoplanets in relation to Jupiter and Neptune;

• Exoplanets that are larger than Jupiter, exoplanet > Jupiter
• Exoplanets that are larger than Neptune but smaller than Jupiter, Neptune < exoplanet < Jupiter
• Exoplanets that are smaller than Neptune, exoplanet < Neptune

As an example, I sorted the radii by value to make finding correlating sizes easier, my search method was;

Sort[{AstronomicalData[#, "Radius"],AstronomicalData[#,"SemimajorAxis"]}->#&/@AstronomicalData["Exoplanet"]]

An extract from the example returns;

{3.63*10^6, 2.25*10^9} -> "KOI961d", {4.65*10^6, 8.75*10^8} -> "KOI961c"...

I found no concept which allowed me to use DeleteCases that allowed me to keep the syntax for naming using #

Answer 1

There are a lot of ways to do that, for example:

name = AstronomicalData["Exoplanet"];
radius = AstronomicalData["Exoplanet", "Radius"];
a = AstronomicalData["Exoplanet", "SemimajorAxis"];
planet = {#, AstronomicalData[#, "Radius"]} & /@ {"Neptune", "Saturn"};

data = DeleteCases[Transpose[{name, radius, a}],
                   {_, Missing["NotAvailable"], _}];
data = Join[data, planet];
data = SortBy[data, #[[ 2]] &];
pos = Position[data, #][[ 1, 1]] & /@ {"Neptune", "Saturn"}

{24, 39}

data = data[[ #]] & /@ {;; 23, 25 ;; 38, 40 ;;};

ListPlot[data[[ ;; , ;; , {2, 3}]], AxesLabel -> {"radius", "semimajoraxis"}, 
         BaseStyle -> {Bold, 15, FontFamily -> "Arial", AbsolutePointSize@10},
         PlotRange -> All]

Answer 2

I was able to produce an alternate method using Part and Select returning my desired results. The alternative requires less variables and I found it easier to work with.

Using Part I was able to selectively filter elements from the compiled lists:

data = Transpose[{AstronomicalData["Exoplanet", "Radius"], AstronomicalData["Exoplanet", "SemimajorAxis"], AstronomicalData["Exoplanet"]}];
data = DeleteCases[data[[All, 1 ;; 2]], {___, _Missing, ___}];
planets = {AstronomicalData[#, "Radius"], AstronomicalData[#, "SemimajorAxis"]} & /@ {"Jupiter", "Neptune", "Earth"};

From there I used Select to further compile lists which I could use to compare elements with:

Select[data, #[[1]] > planets[[1, 1]] &], (* radii>Jupiter*)
Select[data, #[[1]] > planets[[2, 1]] && #[[1]] < planets[[1, 1]] &],  (* Neptune>radii<Jupiter*)
Select[data, #[[1]] > planets[[3, 1]] && #[[1]] < planets[[2, 1]] &], (* radii>Earth<Neptune *)
Select[data, #[[1]] < planets[[3, 1]] &], (* radii<Earth *)

Due to limitations in the results from the database, I selectively disregarded adding the planets into data, however they could be added in one of two ways using:

data = Join[planets,data]; (* join elements *)
planets[[1]], (* add list to plot *)