  The S-shaped magnetic structure in the solar wind formed by the twisting of
magnetic field lines is called a switchback, whose main characteristics are the
reversal of the magnetic field and the significant increase in the solar wind
radial velocity. We identify 242 switchbacks during the first two encounters of
Parker Solar Probe (PSP). Statistics methods are applied to analyze the
distribution and the rotation angle and direction of the magnetic field
rotation of the switchbacks. The diameter of switchbacks is estimated with a
minimum variance analysis (MVA) method based on the assumption of a cylindrical
magnetic tube. We also make a comparison between switchbacks from inside and
the boundary of coronal holes. The main conclusions are as follows: (1) the
rotation angles of switchbacks observed during the first encounter seem larger
than those of the switchbacks observed during the second encounter in general;
(2) the tangential component of the velocity inside the switchbacks tends to be
more positive (westward) than in the ambient solar wind; (3) switchbacks are
more likely to rotate clockwise than anticlockwise, and the number of
switchbacks with clockwise rotation is 1.48 and 2.65 times of those with
anticlockwise rotation during the first and second encounters, respectively;
(4) the diameter of switchbacks is about 10^5 km on average and across five
orders of magnitude (10^3 -- 10^7 km).
