python - Most efficient way to remove entries in a list -

i have massive 4d data set, spread throughout 4 variables, x_list, y_list, z_list, , i_list. each list of n scalars, x, y, , z representing point's position in space, , representing intensity.

i have function picks through , marks negligible points (those intensity low) deletion, setting intensity 0. however, when run on 2-million point set, deletion process takes hours.

currently, using .pop(index) command remove data points, because cleanly. here code:

counter = 0 = 0 entry in i_list     if (i_list[i] == 0):         x_list.pop(i)         y_list.pop(i)         z_list.pop(i)         i_list.pop(i)         counter += 1         print (counter, "points removed")     else         += 1 

how can more efficiently?

i think it'll faster create new empty lists each existing list, , append items them if i_list[i] != 0. time complexity of operations you're doing, , you'll see deleting items o(n), whereas appending o(1). you're doing lot of o(n) deletes pretty large n, slow.

so like:

new_x = [] new_y = [] new_y = [] new_i = []  index in range(len(i_list)):     if i_list[index] != 0:         new_x.append(x_list[index])         new_y.append(y_list[index])         # etc. 

going further, should numpy arrays, subsetting find set of items i_list != 0 fast.