Re: why DateListPlot is so slow?

*To*: mathgroup at smc.vnet.net*Subject*: [mg79962] Re: why DateListPlot is so slow?*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Thu, 9 Aug 2007 05:32:02 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <f9c0ae$5o4$1@smc.vnet.net>

Arkadiusz.Majka at gmail.com wrote: > Hi, > > I have a list (a time series): > > data={{00:00:30,x1},{00:01:00,x2},{00:01:30,x3},....} > > at equally spaced time intervals (30 seconds). The length od data is > 8100 (24 h) > > DateListPlot[data] works fine but takes 28 sec, since > ListPlot[data[[All,2]]] does it in less than 0.1 sec.... > > Can you explain me why DateListPlot is so time consuming? Can we > improve it? As written, data is an invalid Mathematica expression: In[3]:= data = {{00 : 00 : 30, x1}, {00 : 01 : 00, x2}, {00 : 01 : 30, x3}} During evaluation of In[3]:= Syntax::sntxf: "{" cannot be followed by \ "00:00:30,x1}". During evaluation of In[3]:= Syntax::tsntxi: "00:00:30" is \ incomplete; more input is needed. During evaluation of In[3]:= Syntax::sntxi: Incomplete expression; \ more input is needed. Using strings does not solve the issue either In[1]:= data = {{"00:00:30", x1}, {"00:01:00", x2}, {"00:01:30", x3}} Out[1]= {{"00:00:30", x1}, {"00:01:00", x2}, {"00:01:30", x3}} In[2]:= DateListPlot[data] During evaluation of In[2]:= DateListPlot::ntdt: The first argument \ to DateListPlot is not a list of pairs of dates and real values or a \ list of lists of pairs of dates and real values. >> Out[2]= DateListPlot[{{"00:00:30", x1}, {"00:01:00", x2}, {"00:01:30", x3}}] So the question is, "Could you please post an example of the _real_ structure of the dataset you feed to *DateListPlot*?" -- Jean-Marc