Get Nearest Point from each other in pandas dataframe

i have a dataframe:

  routeId  latitude_value  longitude_value
  r1       28.210216        22.813209
  r2       28.216103        22.496735
  r3       28.161786        22.842318
  r4       28.093110        22.807081
  r5       28.220370        22.503500
  r6       28.220370        22.503500
  r7       28.220370        22.503500

from this i want to generate a dataframe df2 something like this:

routeId    nearest
  r1         r3         (for example)
  r2       ...    similarly for all the routes.

The logic i am trying to implement is

for every route, i should find the euclidean distance of all other routes. and iterating it on routeId.

There is a function for calculating euclidean distance.

dist = math.hypot(x2 - x1, y2 - y1)

But i am confused on how to build a function where i would pass a dataframe, or use .apply()

def  get_nearest_route():
    .....
    return df2