Drexel dragonThe Math ForumDonate to the Math Forum


Math Forum
 Ask Dr. Math
 Discussions
 Internet Newsletter
 MathTools
 Problems of the Week
 Teacher2Teacher
 Teacher Exchange
 Workshops

Search All of the Math Forum:
Browse our Internet Mathematics Library

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Software » comp.soft-sys.matlab

Topic: Is there a better way to count number of occurances of string when grouping?
Replies: 6   Last Post: Mar 20, 2012 6:11 PM

Advanced Search
Reply to this Topic Reply to this Topic

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Tom Lane

Posts: 855
Registered: 12/7/04
Re: Is there a better way to count number of occurances of string when grouping?
Posted: Mar 20, 2012 6:11 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

> I have a dataset svdatm with columns:
>
> % dnum (datenum)
> % symid (symbol id - a cell array)
>
> I would like to find the count or number of elements (i.e., symid)
> that occur each day.

In addition to the other suggestions, consider trying

crosstab(svdatm.dnum, svdatm.symid)

I don't know if it would be any faster, and it might require too much memory
if there are lots of unique symid values, but it's a thought.

-- Tom




Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2015. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.