A pre-loaded example dataset in R

Main page: https://www.rdocumentation.org/packages/datasets/versions/3.6.2/topics/UScitiesD

eurodist
##                 Athens Barcelona Brussels Calais Cherbourg Cologne Copenhagen
## Barcelona         3313                                                       
## Brussels          2963      1318                                             
## Calais            3175      1326      204                                    
## Cherbourg         3339      1294      583    460                             
## Cologne           2762      1498      206    409       785                   
## Copenhagen        3276      2218      966   1136      1545     760           
## Geneva            2610       803      677    747       853    1662       1418
## Gibraltar         4485      1172     2256   2224      2047    2436       3196
## Hamburg           2977      2018      597    714      1115     460        460
## Hook of Holland   3030      1490      172    330       731     269        269
## Lisbon            4532      1305     2084   2052      1827    2290       2971
## Lyons             2753       645      690    739       789     714       1458
## Madrid            3949       636     1558   1550      1347    1764       2498
## Marseilles        2865       521     1011   1059      1101    1035       1778
## Milan             2282      1014      925   1077      1209     911       1537
## Munich            2179      1365      747    977      1160     583       1104
## Paris             3000      1033      285    280       340     465       1176
## Rome               817      1460     1511   1662      1794    1497       2050
## Stockholm         3927      2868     1616   1786      2196    1403        650
## Vienna            1991      1802     1175   1381      1588     937       1455
##                 Geneva Gibraltar Hamburg Hook of Holland Lisbon Lyons Madrid
## Barcelona                                                                   
## Brussels                                                                    
## Calais                                                                      
## Cherbourg                                                                   
## Cologne                                                                     
## Copenhagen                                                                  
## Geneva                                                                      
## Gibraltar         1975                                                      
## Hamburg           1118      2897                                            
## Hook of Holland    895      2428     550                                    
## Lisbon            1936       676    2671            2280                    
## Lyons              158      1817    1159             863   1178             
## Madrid            1439       698    2198            1730    668  1281       
## Marseilles         425      1693    1479            1183   1762   320   1157
## Milan              328      2185    1238            1098   2250   328   1724
## Munich             591      2565     805             851   2507   724   2010
## Paris              513      1971     877             457   1799   471   1273
## Rome               995      2631    1751            1683   2700  1048   2097
## Stockholm         2068      3886     949            1500   3231  2108   3188
## Vienna            1019      2974    1155            1205   2937  1157   2409
##                 Marseilles Milan Munich Paris Rome Stockholm
## Barcelona                                                   
## Brussels                                                    
## Calais                                                      
## Cherbourg                                                   
## Cologne                                                     
## Copenhagen                                                  
## Geneva                                                      
## Gibraltar                                                   
## Hamburg                                                     
## Hook of Holland                                             
## Lisbon                                                      
## Lyons                                                       
## Madrid                                                      
## Marseilles                                                  
## Milan                  618                                  
## Munich                1109   331                            
## Paris                  792   856    821                     
## Rome                  1011   586    946  1476               
## Stockholm             2428  2187   1754  1827 2707          
## Vienna                1363   898    428  1249 1209      2105
UScitiesD
##               Atlanta Chicago Denver Houston LosAngeles Miami NewYork
## Chicago           587                                                
## Denver           1212     920                                        
## Houston           701     940    879                                 
## LosAngeles       1936    1745    831    1374                         
## Miami             604    1188   1726     968       2339              
## NewYork           748     713   1631    1420       2451  1092        
## SanFrancisco     2139    1858    949    1645        347  2594    2571
## Seattle          2182    1737   1021    1891        959  2734    2408
## Washington.DC     543     597   1494    1220       2300   923     205
##               SanFrancisco Seattle
## Chicago                           
## Denver                            
## Houston                           
## LosAngeles                        
## Miami                             
## NewYork                           
## SanFrancisco                      
## Seattle                678        
## Washington.DC         2442    2329