I am quite new to LAMMPS and hence my questions might sound naive. Pertaining to the Couette flow example-I am trying to calculate the rate of shear and the velocities of molecules adjacent to the wall. I came across the command variable with an option vx to calculate the velocities of specific atoms as per the id. IS there a way to find out the velocity of all the atoms in a specified region without having to explicitly list ids of each atoms. And also similarly is there a command to find the shear rate directly.