Python：Numpy数组，为每个单元ID获取每100个时间点

I have the following problem. I have an array ( the first 3 element are x,y,z coordinates, the 4th element is the time and the 5th element is the cell ID (1-9). Now i just want every 50th or 100th element of every timepoint FOR EACH CELL ID. This is no duplicate question! So for cell ID 1 I want the row with timepoint 50,100,150 , for Cell ID2 the timepoint 50,100,150 and so on!I have the following problem. I have an array (