python - Strange... What does [::5,0] mean -

i found webpage explaining how use set_xticks , . set_xticklabels.

and set set_xticks , 'set_xticklabels' following...

ax.set_xticks(xx[::5,0]) ax.set_xticklabels(times[::5]) ax.set_yticks(yy[0,::5]) ax.set_yticklabels(dates[::5]) 

what [::5,0] mean..

i don't have idea.....

for numpy array, notation[::5,6] means take 6th column array , in 6th column, every 5th row starting @ first row till last row.

example -

in [12]: n = np.arange(100000) in [17]: n.shape = (500,200)  in [18]: n[::1,2] out[18]: array([    2,   202,   402,   602,   802,  1002,  1202,  1402,  1602,         1802,  2002,  2202,  2402,  2602,  2802,  3002,  3202,  3402,         3602,  3802,  4002,  4202,  4402,  4602,  4802,  .....])  in [19]: n[::5,2] out[19]: array([    2,  1002,  2002,  3002,  4002,  5002,  6002,  ...]) 

reference on numpy array slicing here , if interested.