<[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > Paul McGuire wrote: >> <[EMAIL PROTECTED]> wrote in message >> news:[EMAIL PROTECTED] >> > [snip] >> > >> > no sort() is needed to calculate the median of a list. >> > >> > you just need one temp var. >> > >> >> Ok, I'll bite. How do you compute the median of a list using just a >> single >> temp var? >> >> -- Paul > > hi Paul; well when this was a stats-class assignment (back when pascal > was popular :) i just stepped through the vector and compared it > > (pseudo-code) > > ptr p = [with values]. > > fun median { > var x = 0. > while( *p++) { > if( (*p) > x) x = *p. > } > return x. > } > > of course, pascal is more verbose but that's median() >
No, that's the maximum. The median value is the value that is in the middle of the list when the list is sorted. Many analyses prefer median to mean (also known as "average") because the median is less sensitive to wild outlier points. My original question was in response to your post, that sort() wasn't required but only a temp variable. I am very interested in seeing your solution that does not require the data to be sorted. (This is not just an academic exercise - given a large historical data set, sorting the data is one of the costliest parts of computing the median, and I would greatly appreciate seeing an alternative algorithm.) -- Paul -- http://mail.python.org/mailman/listinfo/python-list
