[Matplotlib-users] Less tedious way to change the x-axis scale intervals with time series data?
Hello,
I'm trying to learn if there is a better or less tedious way of changing the
x-axis time scale interval size when plotting time series data using
MATPLOTLIB.
To account for all the different x-axis intervals that I may end up using, I
usually do the following imports:
from matplotlib.dates import YearLocator, MonthLocator, WeekdayLocator,
DateFormatter, DayLocator
from matplotlib.dates import MO, TU, WE, TH, FR, SA, SU
Then I specify specific intervals by doing the following:
year = YearLocator()
month = MonthLocator(bymonth=range(1,13), bymonthday=1, interval=1)
week = WeekdayLocator(byweekday=MO) # Every MOnday
day= DayLocator(bymonthday=range(1,32), interval=1)
Then apply any of the above formats by doing:
axes.xaxis.set_major_locator(year)
axes.xaxis.set_major_locator(month)
I find all that above too tedious since I may then decide to change the
intervals to something different to experiment.
With R's ggplot2 or Yhat's ggplot, it is very simple and intuitive to change
the x-axis scale interval. You just need to specify the breaks and
minor_breaks interval like so:
scale_x_datetime(labels=date_format("%Y-%m"), breaks="3 months",
minor_breaks="1 month")
I've quit using MATPLOTLIB for plotting time series data because of this.
However, I thought perhaps there is a better way that I am not aware of.
If there is a better way, please educate me! Thanks!
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Re: [Matplotlib-users] linear regression with dates as x axis
Check out linregress from scipy.stats module. Not sure if it will handle
dates. Sample script below:
from scipy.stats import pearsonr from scipy.stats import linregress from
matplotlib import pyplot as plt import numpy as np
sat = np.array([595,520,715,405,680,490,565]) gpa =
np.array([3.4,3.2,3.9,2.3,3.9,2.5,3.5])
fig1 = plt.figure(1) ax = plt.subplot(1,1,1)
pearson = pearsonr(sat, gpa)
plt.scatter(sat,gpa, label="data")
# Get linear regression parameters slope, intercept, r_value, p_value,
std_err = linregress(sat, gpa)
# Format the chart plt.xlabel("SAT Scores") plt.ylabel("GPA")
plt.title("Scatter Plot with Linear Regression Fit\nY=a*X + b\na=%0.4f,
b=%0.4f" % (slope, intercept)) plt.grid()
# Create linear regression x values x_lr = sat
# Create linear regression y values: Y = slope*X + intercept y_lr = slope *
x_lr + intercept
print "Pearson correlation coefficient: ", pearson[0] print "Fit x-values:
", str(x_lr) print "Fit y-values: ", str(y_lr) print "Fit slope: ",slope
print "Fit intercept: ", intercept plt.plot(x_lr, y_lr, label="fit")
plt.legend()
plt.show()
Regards,
Daniel
On Jun 13, 2012 12:32 PM, "Chris Withers" wrote:
> Hi all,
>
> I have some time series of disk usage that I'd like to do a linear
> regression on an plot on a nice graph with Mb used on the y-axis and
> date on the x axis.
>
> I tried to use pylab.polyfit(dates, usage) where:
>
> dates = [datetime(x, y, z), datetime(a, b, c), ...]
> usage = [12123234, 2234235235, ...]
>
> ...but polyfit doesn't like the dates.
>
> How should I do this?
>
> Any example of a nice plot and linear regression using matplotlib?
>
> cheers,
>
> Chris
>
> --
> Simplistix - Content Management, Batch Processing & Python Consulting
> - http://www.simplistix.co.uk
>
>
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Re: [Matplotlib-users] linear regression with dates as x axis
Sorry looks like my smartphone's copy/paste removed carriage return in certain places in the script :-( On Jun 13, 2012 12:32 PM, "Chris Withers" wrote: > Hi all, > > I have some time series of disk usage that I'd like to do a linear > regression on an plot on a nice graph with Mb used on the y-axis and > date on the x axis. > > I tried to use pylab.polyfit(dates, usage) where: > > dates = [datetime(x, y, z), datetime(a, b, c), ...] > usage = [12123234, 2234235235, ...] > > ...but polyfit doesn't like the dates. > > How should I do this? > > Any example of a nice plot and linear regression using matplotlib? > > cheers, > > Chris > > -- > Simplistix - Content Management, Batch Processing & Python Consulting > - http://www.simplistix.co.uk > > > -- > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > ___ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
Re: [Matplotlib-users] Scatter legend woes.
Are you trying to make 9 scatter plots? In your for loop, if you are trying to make a set of x values and a set of y values, then I think this is wrong. Since you didn't provide import statements I don't know which rand() function you are using. Assuming it is scipy.rand(), you will only have one x value and one y value, not much of scatter chart with just one point :-) Otherwise, Mike's suggestion is valid. Regards, Daniel On Jun 13, 2012 3:35 PM, "Steven Boada" wrote: > Whoops, I forgot to change the subject. Sorry list. > > List, > > I'm making a scatter plot using a for loop. Here's a simple example.. > > for i in range(10): > x=rand() > y=rand() > scatter(x,y,label='point') > > legend() > show() > > > When you do this, you get a legend entry for every single point. In this > case, I get 9 entries in my legend. > > Is there a way to only get a single entry? I have looked into creating > the legends by hand, but I'm not having much luck. Googling, only turned > up a single example of someone else with the same problem. > > Help me list, you're my only hope. > > Steven > > On 06/13/2012 01:33 PM, Eric Firing wrote: > > On 06/13/2012 07:31 AM, jonasr wrote: > >> Hi, > >> > >> im actually trying to make a countour plot Z=f(X,Y) from two variables > X,Y . > >> My Problem is that i have to use a logarithmic scale for the Z values. > >> If i plot the data with the logarithmic scale it gets pretty ugly, > because i > >> have a lot of values which are zero, > >> which means on the log scale the value goes to -inf. > >> Here is an example what i mean > >> > >> http://www.imagebanana.com/view/qh1khpxp/example.png > >> > >> I acutally have no idea how to make the plot look better, > >> maybe somebody has an idea ? > > Use np.ma.masked_less to mask out values below some threshold before > > taking the log. > > > > e.g., > > > > import matplotlib.pyplot as plt > > import numpy as np > > x = np.arange(0, 1, 0.01) > > y = np.arange(0, 8, 0.05) > > X, Y = np.meshgrid(x, y) > > Z = 10 ** (-5 + 11 * X * np.sin(Y)) > > Z = np.ma.masked_less(Z, 1e-4) > > Zlog = np.ma.log10(Z) > > CS = plt.contourf(X, Y, Zlog, levels=np.arange(-3, 5.01, 1.0), > > extend='both') > > plt.colorbar() > > > > > > > > Eric > > > >> thank you > > > > > -- > > Live Security Virtual Conference > > Exclusive live event will cover all the ways today's security and > > threat landscape has changed and how IT managers can respond. Discussions > > will include endpoint security, mobile security and the latest in malware > > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > > ___ > > Matplotlib-users mailing list > > Matplotlib-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > > > > -- > Steven Boada > Dept. Physics and Astronomy > Texas A&M University > bo...@physics.tamu.edu > > > > -- > Live Security Virtual Conference > Exclusive live event will cover all the ways today's security and > threat landscape has changed and how IT managers can respond. Discussions > will include endpoint security, mobile security and the latest in malware > threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ > ___ > Matplotlib-users mailing list > Matplotlib-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/matplotlib-users > -- Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/___ Matplotlib-users mailing list Matplotlib-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-users
