matplotlib: Plotting a graph against time

[Durand]

Hi,

I'm trying to plot a simple graph against date or time using matplotlib. I've read about date_plot but I'm not really sure how to use it. At the moment, I have some data arranged into lists, where list1 contains x values (time) and list2 contains y values just like is needed for the normal plot function. The time values are simply the output of datetime.date.t oday(), etc which I don't mind changing the format of.

My question is, how do I plot the graph with list1 on the x axis and list2 on the y axis. Using plot and unixtime I get a very ugly scale as is to be expected so I want to know how to use the date_plot function efficiently. At the moment, I'm only concerned about the actual plotting but help with Locater Ticks (Months and Years) is also very appreciated.

Thanks a lot!

[arsyed]

Re: matplotlib: Plotting a graph against time

On Jul 19, 3:09 pm, Durand <dura...@gmail. comwrote:

Hi,
>
I'm trying to plot a simple graph against date or time using matplotlib. I've read about date_plot but I'm not really sure how to use it. At the moment, I have some data arranged into lists, where list1 contains x values (time) and list2 contains y values just like is needed for the normal plot function. The time values are simply the output of datetime.date.t oday(), etcwhich I don't mind changing the format of.
>
My question is, how do I plot the graph with list1 on the x axis and list2 on the y axis. Using plot and unixtime I get a very ugly scale as is to be expected so I want to know how to use the date_plot function efficiently.At the moment, I'm only concerned about the actual plotting but help with Locater Ticks (Months and Years) is also very appreciated.
>
Thanks a lot!

I'm not sure if this is what you're looking for, but here's a quick
sample that uses plot_date to plot some random values.

import pylab, random
from datetime import datetime, timedelta

today = datetime.now()

dates = [today + timedelta(days= i) for i in range(10)]
values = [random.randint( 1, 20) for i in range(10)]
pylab.plot_date (pylab.date2num (dates), values, linestyle='-')

[Durand]

Re: matplotlib: Plotting a graph against time

On Jul 20, 8:55 am, arsyed <ars...@gmail.c omwrote:

On Jul 19, 3:09 pm, Durand <dura...@gmail. comwrote:
>

Hi,

>

I'm trying to plot a simple graph against date or time using matplotlib.. I've read about date_plot but I'm not really sure how to use it. At the moment, I have some data arranged into lists, where list1 contains x values (time) and list2 contains y values just like is needed for the normal plot function. The time values are simply the output of datetime.date.t oday(), etc which I don't mind changing the format of.

>

My question is, how do I plot the graph with list1 on the x axis and list2 on the y axis. Using plot and unixtime I get a very ugly scale as is tobe expected so I want to know how to use the date_plot function efficiently. At the moment, I'm only concerned about the actual plotting but help with Locater Ticks (Months and Years) is also very appreciated.

>

Thanks a lot!

>
I'm not sure if this is what you're looking for, but here's a quick
sample that uses plot_date to plot some random values.
>
import pylab, random
from datetime import datetime, timedelta
>
today = datetime.now()
>
dates = [today + timedelta(days= i) for i in range(10)]
values = [random.randint( 1, 20) for i in range(10)]
pylab.plot_date (pylab.date2num (dates), values, linestyle='-')

Oooh, this is almost what I want but I'm not really sure how I'd
incorporate this into real dates...
If I have a list of dates like ['2008-07-18 14:36:53.494013 ',
'2008-07-20 14:37:01.508990 ', '2008-07-28 14:49:26.183256 '], how would
I convert it to a format that pylab can understand? When I tried
type(datetime.n ow()) it gave me datetime.dateti me whereas the objects
in this list are strings...Am I doing something wrong here?