Thread: [Matplotlib-users] My Legend keeps growing! Help

I am trying make a plot that is in a loop and replots when new data is
updated.

#IN A LOOP

    fig = plt.figure(1,[10,10])
    fig.clf
    
    prop = matplotlib.font_manager.FontProperties(size=8)

    xMin = dates[1]
    xMax = dates[-1]

    #temperature plot   
    yMin = min(temperatureSQLData)
    yMax = max(temperatureSQLData)
    
    minTemperature = "Min = %.3f " % min(temperatureSQLData) + 'deg ' + 'C'  
    minTemperatureIndex = temperatureSQLData.index(yMin)

    maxTemperature = "Max = %.3f " % max(temperatureSQLData) + 'deg ' + 'C'
    maxTemperatureIndex = temperatureSQLData.index(yMax)

    ax1 = fig.add_subplot(511)
    ax1.cla

    plt.hold(True)
    plt.plot(dates,temperatureSQLData,'r')
    plt.plot(dates[minTemperatureIndex],yMin,'ro',label=minTemperature)
    plt.plot(dates[maxTemperatureIndex],yMax,'bo',label=maxTemperature)
    plt.hold(False)
    
    plt.title("Water Conditions for the last 7 Days.")

    plt.xlim([xMin,xMax])
    plt.ylim([yMin-1,yMax+1])
    plt.ylabel('Temperature')
    ax1.legend(numpoints=1,prop=prop)

    dateFormat = mpl.dates.DateFormatter('%m/%d/%Y')
    ax1.xaxis.set_major_formatter(dateFormat)
    daysLocation = mpl.dates.DayLocator()
    ax1.xaxis.set_major_locator(daysLocation)
    hoursLocation = mpl.dates.HourLocator(interval=4)
    ax1.xaxis.set_minor_locator(hoursLocation)

The problem is that the number of items in my legend grows with each
iteration of the loop. Any help would be appreciated!
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Hi ,


On Thu, Aug 26, 2010 at 05:47, dcarroll <spa...@gm...> wrote:
>
> I am trying make a plot that is in a loop and replots when new data is
> updated.
>
> #IN A LOOP
>
>    fig = plt.figure(1,[10,10])
>    fig.clf
>
>    prop = matplotlib.font_manager.FontProperties(size=8)
>
>    xMin = dates[1]
>    xMax = dates[-1]
>
>    #temperature plot
>    yMin = min(temperatureSQLData)
>    yMax = max(temperatureSQLData)
>
>    minTemperature = "Min = %.3f " % min(temperatureSQLData) + 'deg ' + 'C'
>    minTemperatureIndex = temperatureSQLData.index(yMin)
>
>    maxTemperature = "Max = %.3f " % max(temperatureSQLData) + 'deg ' + 'C'
>    maxTemperatureIndex = temperatureSQLData.index(yMax)
>
>    ax1 = fig.add_subplot(511)
>    ax1.cla
>
>    plt.hold(True)
>    plt.plot(dates,temperatureSQLData,'r')
>    plt.plot(dates[minTemperatureIndex],yMin,'ro',label=minTemperature)
>    plt.plot(dates[maxTemperatureIndex],yMax,'bo',label=maxTemperature)
>    plt.hold(False)
>
>    plt.title("Water Conditions for the last 7 Days.")
>
>    plt.xlim([xMin,xMax])
>    plt.ylim([yMin-1,yMax+1])
>    plt.ylabel('Temperature')
>    ax1.legend(numpoints=1,prop=prop)
>
>    dateFormat = mpl.dates.DateFormatter('%m/%d/%Y')
>    ax1.xaxis.set_major_formatter(dateFormat)
>    daysLocation = mpl.dates.DayLocator()
>    ax1.xaxis.set_major_locator(daysLocation)
>    hoursLocation = mpl.dates.HourLocator(interval=4)
>    ax1.xaxis.set_minor_locator(hoursLocation)
>
> The problem is that the number of items in my legend grows with each
> iteration of the loop. Any help would be appreciated!



You can select yourself what you want to include in the legend by
creating the legend as follows:


**************************************
legendEntries=[]             # list of plots that are going to be in
the legend
legendText=[]   # list of text messages for the legend

thisPlot = plot(x,y,'b*') # a plot command

legendEntries.append(thisPlot) # only do this for the plots you want
to add to the legend
legendText.append("legend text")    # only this for the plots you want
to add to the legend

 lgd = legend(legendEntries,legendText,numpoints=1,prop=props,loc='upper
right') # example of how to draw the legend

**************************************

so you could clean the legendEntries and legendText at the beginning
of every loop by calling
legendEntries=[]
legendText=[]

Or if the legend is every time the same you can only create it in the
first iteration of the loop and then do not change the legendEntries
or legendtext any more.

Tinne

On Thu, Aug 26, 2010 at 8:23 AM, Tinne De Laet
<tin...@me...> wrote:
> On Thu, Aug 26, 2010 at 05:47, dcarroll <spa...@gm...> wrote:
>>
>> I am trying make a plot that is in a loop and replots when new data is
>> updated.
>>
>> #IN A LOOP
>>
>>    fig = plt.figure(1,[10,10])
>>    fig.clf
>>
>>    prop = matplotlib.font_manager.FontProperties(size=8)
>>
>>    xMin = dates[1]
>>    xMax = dates[-1]
>>
>>    #temperature plot
>>    yMin = min(temperatureSQLData)
>>    yMax = max(temperatureSQLData)
>>
>>    minTemperature = "Min = %.3f " % min(temperatureSQLData) + 'deg ' + 'C'
>>    minTemperatureIndex = temperatureSQLData.index(yMin)
>>
>>    maxTemperature = "Max = %.3f " % max(temperatureSQLData) + 'deg ' + 'C'
>>    maxTemperatureIndex = temperatureSQLData.index(yMax)
>>
>>    ax1 = fig.add_subplot(511)
>>    ax1.cla
>>
>>    plt.hold(True)
>>    plt.plot(dates,temperatureSQLData,'r')
>>    plt.plot(dates[minTemperatureIndex],yMin,'ro',label=minTemperature)
>>    plt.plot(dates[maxTemperatureIndex],yMax,'bo',label=maxTemperature)
>>    plt.hold(False)
>>
>>    plt.title("Water Conditions for the last 7 Days.")
>>
>>    plt.xlim([xMin,xMax])
>>    plt.ylim([yMin-1,yMax+1])
>>    plt.ylabel('Temperature')
>>    ax1.legend(numpoints=1,prop=prop)
>>
>>    dateFormat = mpl.dates.DateFormatter('%m/%d/%Y')
>>    ax1.xaxis.set_major_formatter(dateFormat)
>>    daysLocation = mpl.dates.DayLocator()
>>    ax1.xaxis.set_major_locator(daysLocation)
>>    hoursLocation = mpl.dates.HourLocator(interval=4)
>>    ax1.xaxis.set_minor_locator(hoursLocation)
>>
>> The problem is that the number of items in my legend grows with each
>> iteration of the loop. Any help would be appreciated!
>
>
>
> You can select yourself what you want to include in the legend by
> creating the legend as follows:

You can also leave out the label, or in a loop like this,
conditionally assign a label of '_nolegend_', which suppresses adding
it to the legend. This example shows how the different options work:

import numpy as np
import matplotlib.pyplot as plt
x1,y1 = np.random.rand(2,10)
x2,y2 = np.random.rand(2,10)
x3,y3 = np.random.rand(2,10)
x4,y4 = np.random.rand(2,10)
plt.plot(x1, y1, label='first')
plt.plot(x2, y2) # No label, so not included
plt.plot(x3, y3, label='_nolegend_') # Actively suppress
plt.plot(x4, y4, label='fourth')
plt.legend() # Only shows lines 'first' and 'fourth'

Ryan

-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma

On Wed, Aug 25, 2010 at 10:47 PM, dcarroll <spa...@gm...> wrote:
>
> I am trying make a plot that is in a loop and replots when new data is
> updated.
>
> #IN A LOOP
>
>    fig = plt.figure(1,[10,10])
>    fig.clf

It looks like the problem is that you are not clearing your figure.
clf is a function, so you need

  fig.clf()

JDH