the graph of the international trade relations

Mathematica has provided excellent database of the countries in the function CountryData. I am particularly interested in the trade relations. CountryData[country, "ImportPartners"] and CountryData[country, "ExportPartners"] produce the leading import and export partners of the country. We can construct a graph based on the global trade relations.

trade = 
  Tally[Sort /@ 
    Flatten[Tuples[{{#}, 
         Select[Flatten[{CountryData[#, 
              "ImportPartners"] /. _Missing -> Null, 
            CountryData[#, "ExportPartners"] /. _Missing -> Null}], 
          MemberQ[CountryData[], #] &]}] & /@ CountryData[], 1]];

tradegraph = 
 Graph[Thread[
   trade[[All, 1, 1]] \[UndirectedEdge] 
    trade[[All, 1, 2]]], 
  EdgeWeight -> trade[[All, 2]]]

Fig. 1, the graph of the international trade relations.

We can make it more accessible by coloring the countries.

by continent:

Row[
 {Graph[Thread[
    trade[[All, 1, 1]] \[UndirectedEdge] 
     trade[[All, 1, 2]]], 
   EdgeWeight -> trade[[All, 2]],
   VertexShapeFunction -> ({ColorData[3, 
        First@First@
          Position[CountryData["Continents"], 
           CountryData[#2, "Continent"] ]], Opacity[.8], 
       EdgeForm[{Thin, LightGray}], Disk[#, .08], Darker@Red, 
       Opacity[1.0], 
       Text[Style[CountryData[#2, "CountryCode"], Bold], #1] } &), 
   ImageSize -> 800],
  Graphics[
   MapIndexed[{ColorData[3, First@#2], 
      Text[Style[
        StringJoin[
         Riffle[StringCases[#1, RegularExpression["[A-Z][a-z]+"]], 
          " "]], Bold, 22], {40, First@#2*60}]} &, 
    CountryData["Continents"]],
   ImageSize -> {Automatic, 300}]
  }]

Fig. 2,  (Colored by Continent) the graph of the international trade relations.

by trade values, 

Fig. 3,  (Colored by Continent) the graph of the international trade relations.

Fig. 4, colored by the import and export amount separated.

We can explore some further graph structures inside the international trade relations. What we focus here is the the graph communities. The communities characterize the clustering property of a graph. Apply the Mathematica function FindGraphCommunities[], we obtain several trade clusters. The leading 3 communities correspond to the three known trade zones: the Transatlantic Trade Zone including US. and the European Union; the Asia-Pacific Trade Zone including China, Japan, Korea Australia and the ASEANs; the South-America Trade Zone including Brazil, Argentina etc. Our conclusion is further justified if we color the countries inside the trade zone by their continent (Fig. 6).

Fig. 5, the graph communities of the international trade relations.

Fig. 6, trade communities and the geographic distribution.