Hi Once again I need your help to understand one topic concerning slicing topic, or in other word I do not understand how it works in that particular (but common) case; I'm trying to reassign the 4 first values in an array: * If I use [:3] I'm expecting to have 4 values (index 0 to 3 included) * Ditto with [0:3] * If I use [3:] I have 2 values as expected (indexes 3 and 4) Both code and results are presented here after, so this way of thinking worked so far in other calculations, and it fails here? Thanks Paul ps : extraction from the doc (https://docs.scipy.org/doc/numpy/reference/arrays.indexing.html) _[... all indices are zero-based ...]_ CODE: x = np.random.rand(5); print("x = ",x); ## test 1 print("partials =\n %s \nor %s \nor %s" %( x[:3], x[0:3], x[3:]) ) print("x[0] : ",x[0]); print("x[1] : ",x[1]); print("x[2] : ",x[2]); print("x[3] : ",x[3]) ## test 2 y = np.ones(4); print("y = ",y) x[0:4] = y print("x final = ",x) PROVIDE: x = [ 0.39921271 0.07097531 0.37044695 0.28078163 0.11590451] partials = [ 0.39921271 0.07097531 0.37044695] or [ 0.39921271 0.07097531 0.37044695] or [ 0.28078163 0.11590451] x[0] : 0.39921271184 x[1] : 0.0709753133926 x[2] : 0.370446946245 x[3] : 0.280781629 y = [ 1. 1. 1. 1.] x final = [ 1. 1. 1. 1. 0.11590451]