Speed up python's struct.unpack

Question

I am trying to speed up my script. It basically reads a pcap file with Velodyne\'s Lidar HDL-32 information and allows me to get X, Y, Z, and Intensity values. I have profiled m

Answer 1

You can unpack the raw distanceInformation and intensity values together in one call. Especially because you're just putting them into a list together: that's what unpack() does when it unpacks multiple values. In your case, you need to then multiple the distanceInformation by 0.002, but you might save time by leaving this until later, because you can use iter_unpack() to parse the whole list of raw pairs in one call. That function gives you a generator, which can be sliced with itertools.islice() and then turned into a list. Something like this:

laser_iter = struct.iter_unpack('

Unfortunately this is a little harder to read, so you might want to find a way to spread this out into more lines of code, with more descriptive variable names, or add a comment for the future when you forget why you wrote this…