Skip to main content

geography - How to find what you want in curated data?


The following gives a list of all counties in the state of Maryland.


counties = EntityClass["AdministrativeDivision", "USCountiesMaryland"]
   ["Name"];
Flatten[StringDrop[StringCases[#, __ ~~ ","], -1] & /@ counties]

  (* {Allegany County, Maryland,Anne Arundel County, Maryland,

    Baltimore (independent city), Maryland,Baltimore County,
    Maryland,Calvert County, Maryland,Caroline County, Maryland,
    Carroll County, Maryland,Cecil County, Maryland,Charles County,
    Maryland,Dorchester County, Maryland,Frederick County, Maryland,Garrett
    County, Maryland,Harford County, Maryland,Howard County, Maryland,
    Kent County, Maryland,Montgomery County, Maryland,Prince George's
    County, Maryland,Queen Anne's County, Maryland,Somerset County,
    Maryland,St. Mary's County, Maryland,Talbot County, Maryland,
    Washington County, Maryland,Wicomico County, Maryland,Worcester 
    County, Maryland} *)


The first line is based on code another person wrote. I have seen use of "AdministrativeDivision" and "Name" before. How would I determine that "USCountiesMaryland" is needed? Also, how does one know when EntityClass needs more than one argument?



Answer



(See also this: http://reference.wolfram.com/language/guide/KnowledgeRepresentationAndAccess.html)


This is all in the docs, but maybe it's good to lay out here.


If you need classes, use EntityClassList:


EntityClassList["AdministrativeDivision"] // CanonicalName // 
 Take[#, 5] &

{"ADM1", "ADM2", "ADM3", "AllUSStatesAndTerritories", \

"AllUSStatesPlusDC"}

If you need properties, use EntityProperties:


EntityProperties["AdministrativeDivision"] // CanonicalName // 
 Take[#, 5] &

{"AccommodationAndFoodServicesSales", "AggravatedAssault", \
"AggravatedAssaultRate", "AggregateHouseholdIncome", "AnnualBirths"}

If you want straight-up entities, use EntityList:



EntityList["Aircraft"] // CanonicalName // Take[#, 5] &

{"RB1", "CAP1", "TSR2", "3ISkyArrow", "3SigmaNearchos"}

Note that EntityList can be applied to a class, too and EntityProperties can be applied to individual entities.


If you want the type name, use EntityTypeName, see also CanonicalName and CommonName


I don't actually know how to get a list of every EntityPropertyClass for an entity type without direct access to the EntityStore


If you want an Association or Dataset of your data, you can specify that to EntityValue. This works even for custom entities provided via EntityStore:


EntityValue[Entity["AirlineSafety", "Aer Lingus"], "Association"]


<|EntityProperty["AirlineSafety", "Label"] -> "Aer Lingus", 
 EntityProperty["AirlineSafety", "Airline"] -> "Aer Lingus", 
 EntityProperty["AirlineSafety", "AvailableSeatKilometersPerWeek"] -> 
  320906734, EntityProperty["AirlineSafety", "Incidents85to99"] -> 2, 
 EntityProperty["AirlineSafety", "FatalAccidents85to99"] -> 0, 
 EntityProperty["AirlineSafety", "Fatalities85to99"] -> 0, 
 EntityProperty["AirlineSafety", "Incidents00to14"] -> 0, 
 EntityProperty["AirlineSafety", "FatalAccidents00to14"] -> 0, 
 EntityProperty["AirlineSafety", "Fatalities00to14"] -> 0|>


Note that this also can be used on types or classes, e.g,


EntityClass["Airline", "Departures" -> GreaterThan[1000000]][
  "Association"] // Map[Take[#, 3] &]

<|Entity["Airline", 
   "SouthwestAirlinesCo::tcv64"] -> <|EntityProperty["Airline", 
     "AircraftFuel"] -> Quantity[1.53*10^9, "Gallons"], 
   EntityProperty["Airline", "AirlineID"] -> "19393", 
   EntityProperty["Airline", "Airtime"] -> 
    Quantity[36319489/20, "Hours"]|>|>

Comments

Post a Comment

Popular posts from this blog

mathematical optimization - Minimizing using indices, error: Part::pkspec1: The expression cannot be used as a part specification

I want to use Minimize where the variables to minimize are indices pointing into an array. Here a MWE that hopefully shows what my problem is. vars = u@# & /@ Range[3]; cons = Flatten@ { Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; Minimize[{Total@((vec1[[#]] - vec2[[u[#]]])^2 & /@ Range[1, 3]), cons}, vars, Integers] The error I get: Part::pkspec1: The expression u[1] cannot be used as a part specification. >> Answer Ok, it seems that one can get around Mathematica trying to evaluate vec2[[u[1]]] too early by using the function Indexed[vec2,u[1]] . The working MWE would then look like the following: vars = u@# & /@ Range[3]; cons = Flatten@{ Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; NMinimize[ {Total@((vec1[[#]] - Indexed[vec2, u[#]])^2 & /@ R...
Post a Comment
Read more

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

What is and isn't a valid variable specification for Manipulate?

I have an expression whose terms have arguments (representing subscripts), like this: myExpr = A[0] + V[1,T] I would like to put it inside a Manipulate to see its value as I move around the parameters. (The goal is eventually to plot it wrt one of the variables inside.) However, Mathematica complains when I set V[1,T] as a manipulated variable: Manipulate[Evaluate[myExpr], {A[0], 0, 1}, {V[1, T], 0, 1}] (*Manipulate::vsform: Manipulate argument {V[1,T],0,1} does not have the correct form for a variable specification. >> *) As a workaround, if I get rid of the symbol T inside the argument, it works fine: Manipulate[ Evaluate[myExpr /. T -> 15], {A[0], 0, 1}, {V[1, 15], 0, 1}] Why this behavior? Can anyone point me to the documentation that says what counts as a valid variable? And is there a way to get Manpiulate to accept an expression with a symbolic argument as a variable? Investigations I've done so far: I tried using variableQ from this answer , but it says V[1...
Post a Comment
Read more