gonzlobo schrieb: > Greetings, and happyNewYear to all. > > I picked up Python a few weeks ago, and have been able to parse large > files and process data pretty easily, but I believe my code isn't too > efficient. I'm hoping dictionaries will help out, but I'm not sure the > best way to implement them. > > I've been using a bunch of nested if/elif/else statements to select > slices (0317 & 03de) from a file, then parse the data (aa, hh, bb, > d2-d9) into parameters (a = airspeed, h = heading) & flags. > > #sample file contents > 0000007d 03 0317 aa aa aa aa aa hh hh hh bb bb > 0000007e 06 03de d2 d3 d4 d5 d6 d7 d8 d9 10 11 > > # some pseudo code > if PID == '03de': > flapsCmd = int(d3, 16) > if flapsCmd == 0xc0: > <flaps up code> > elif flapsCmd == 0x03: > <flaps down code> > if PID == '0317': > airspeed == 'combine aa for airspeed & multiply by 0.1' > heading == 'combine hh for heading' > mach == 'combine bb for mach & multiply by 0.01' > > Might dictionaries help in this case... say Label0317(parameterName, > slice (d3), scaleFactor(0.1))... I'd like to use them if they'll > replace the dozens of nested conditionals. I have roughly 75 > different parameters to decode from a file containing ~2.5 million > lines of data. > > I know my pseudo code lacks details, but hopefully I'm getting my > point across... > > (I suppose switch/select/case statements would help a bit, but python > doesn't seem to use them... not to start a religious war or anything).
The dictionary approach certainly will be speedier - lookup should usually be O(1) instead of O(n) for the if-elif-chain. Diez -- http://mail.python.org/mailman/listinfo/python-list
