  We present a statistical analysis for the characteristics and spatial
evolution of the interplanetary discontinuities (IDs) in the solar wind, from
0.13 to 0.9 au, by using the Parker Solar Probe measurements on Orbits 4 and 5.
3948 IDs have been collected, including 2511 rotational discontinuities (RDs)
and 557 tangential discontinuities (TDs), with the remnant unidentified. The
statistical results show that (1) the ID occurrence rate decreases from 200
events/day at 0.13 au to 1 events/day at 0.9 au, following a spatial scaling
r-2.00, (2) the RD to TD ratio decreases quickly with the heliocentric
distance, from 8 at r<0.3 au to 1 at r>0.4 au, (3) the magnetic field tends to
rotate across the IDs, 45{\deg} for TDs and 30{\deg} for RDs in the pristine
solar wind within 0.3 au, (4) a special subgroup of RDs exist within 0.3 au,
characterized by small field rotation angles and parallel or antiparallel
propagations to the background magnetic fields, (5) the TD thicknesses
normalized by local ion inertial lengths (di) show no clear spatial scaling and
generally range from 5 to 35 di, and the normalized RD thicknesses follow
r-1.09 spatial scaling, (6) the outward (anti-sunward) propagating RDs
predominate in all RDs, with the propagation speeds in the plasma rest frame
proportional to r-1.03. This work could improve our understandings for the ID
characteristics and evolutions and shed light on the study of the turbulent
environment in the pristine solar wind.
