Python: make dual vector dot-product more pythonic Post: 303041217

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Top Forums Shell Programming and Scripting Python: make dual vector dot-product more pythonic Post 303041217 by figaro on Monday 18th of November 2019 04:18:23 PM

11-18-2019

Registered User

Python: make dual vector dot-product more pythonic

I have this dot product, calculating weighted means, and is applied to two columns in a list:

Code:

# calculate weighted values in sequence
for i in range(len(temperatures)-len(weights)):
  temperatures[i].append(sum([weights[j]*temperatures[i+j][5] for j in range(len(weights))]))
  temperatures[i].append(sum([weights[j]*temperatures[i+j][6] for j in range(len(weights))]))

The calculation is a running dot-product, ie the list of temperature samples is far larger than the list of weights, hence the correction of subtracting len(weights) at the end of the main loop.
This traverses the list of weights twice, which is inefficient and degrades performance. How could this be done in a more pythonic way?

I also have concerns about the main loop. Would this be considered more pythonic?:

Code:

# calculate weighted values in sequence
for i in range(len(temperatures)):
   try:
      # weighted calculation here
   except:
      # do nothing, because array out of bounds

Last edited by figaro; 11-18-2019 at 06:01 PM.. Reason: Emphasise the fact that the lists are not of the same length, ie the dot product calculates a running weighted mean.

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LEARN ABOUT DEBIAN

makeweights

MAKEWEIGHTS(6)							   Games Manual 						    MAKEWEIGHTS(6)

NAME

       makeweights - generate a GNU Backgammon binary weights file

SYNOPSIS

       makeweights [[-f] output [input]]

DESCRIPTION

       makeweights generates GNU Backgammon binary weights file from a text input file.  By default, it reads input from standard input and writes
       output to standard output, but input and output files may be specified on the command line.  It is only of interest if you want to regener-
       ate the gnubg.wd database from a modified gnubg.weights file.

OPTIONS

       -f     This option may be given for compatibility with the options of other GNU Backgammon programs but is ignored.

EXAMPLES

       To generate gnubg.wd from gnubg.weights:

	   makeweights gnubg.wd gnubg.weights

SEE ALSO

       gnubg(6)

AUTHORS

       Joseph Heled, Oystein Johansen, Jorn Thyssen, and Gary Wong, with the assistance of many others <bug-gnubg@gnu.org>.

       This manual page was written by Russ Allbery <rra@debian.org>, for the Debian GNU/Linux system (but may be used by others).  It may be
       redistributed and/or modified under the terms of version 3 or later of the GNU General Public License as published by the Free Software
       Foundation (the same license as GNU Backgammon).

								    2008-02-16							    MAKEWEIGHTS(6)