  We consider conductance mapping of the snake-orbits confined along the n-p
junction defined in graphene by the electrostatic doping in the quantum Hall
regime. We explain the periodicity of conductance oscillations at the magnetic
field and the Fermi energy scales by the properties of the n-p junction as a
conducting channel. We evaluate the conductance maps for a floating gate
scanning the surface of the device. In the quantum Hall conditions the currents
flow near the edges of the sample and along the n-p junction. The conductance
mapping resolves only the n-p junction and not the edges. The conductance
oscillations along the junction are found in the maps with periodicity related
to the cyclotron orbits of the scattering current. Stronger probe potentials
provide support to localized resonances at one of the sides of the junction
with current loops that interfere with the n-p junction currents. The
interference results in a series of narrow lines parallel to the junction with
positions that strongly depend on the magnetic field through the Aharonov-Bohm
effect. The consequences of a limited transparency of finite width n-p
junctions are also discussed.
