Graph Dates and Values
gagsl-py2 at yahoo.com.ar
Tue Mar 10 15:40:13 CET 2009
En Tue, 10 Mar 2009 05:08:41 -0200, brianrpsgt1 <brianlong at cox.net>
> I am trying to plot dates and values on a graph using matplotlib.
> Below is the code. I can run this and it works great, until I get to
> about 2000 rows from the DB. Things really start to slow down. I
> have successfully plotted up to 5000 rows from the DB, but it is very
> slow. I am attempting to plot values for a day, which would be equal
> to 84600 records. Is there a more efficient may to accomplish this?
(isn't it 86400?)
> for s in value_data:
> dates = mdates.date2num([s])
> plt.plot([dates],[s], 'bo', ms=6)
Without looking at the matplotlib docs, the above  suggests that both
date2num and plt.plot take a list of values to act upon, and you're
feeding one point at a time. Probably you end up creating one series per
point (instead of a single series with many points). I guess something
like this should work:
x, y = zip(*value_data) # "transpose"
dates = mdates.date2num(x)
plt.plot(dates, y, 'bo', ms=6)
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