[R] GIS Help: distance calculation based on ZIP Code

[XINLI LI]

Dear R Group Users:

    If there is a resource or easy way to calculate the distance
between zipcodes, for example, if I have the zipcode for 200 patients,
and the zipcode of a hospital, how to calculate the travel distance of
these individual patient to the hospital based on the zipcode. Your
input will be greatly appreciated.

   Thanks and regards,

   XING