Re: [Matplotlib-users] trig plot from event?

Stephen George Thu, 22 Mar 2007 17:51:05 -0800

Creating a 'simplified' example (not really) to demonstrate the problem


Zoom in on one of the constant speed movements.(upper graph)

psd (lower graph) will still be showing spectrum of whole data file.

click 'n release any mouse button in the upper graph, and only thenwill the lower graph redraw with the new limits.


zoom out, try again on other constant speed movement.

how to get lower graph to redraw on new limits after the zoom, withouthaving to click the upper graph again?


Steve

I have two plots.
first one is velocity data from servo controller (freq) - plantreciprocates back and forth so we got turn data in there as wellsecond one is psd (power spectral density) so we can see where we gotresonances etc.
When we zoom in on on section of first plot (say the forward movement),I'd like to recalc the psd with only the data that's been zoomed in on.
Everything kind of works except for somewhere to trigger from.
I had thought of trying resize_event - however I cannot get thisworking- see other post.
I played with button_release_event to get the code basically working,however that event occurs before the first graph gets resized, so theregion I am calculating the psd on is wrong, maybe because I am using
xlim = myAxis.get_xlim()
to find the limits of the first graph (which hasn't been re-drawn yet)
Is there some way I can hook the re-calc/draw of psd to the zooming offirst graph?
Previously with 2 plot commands, I have used subplot(212, sharex=p1), tohook the two graphs together on the xaxishowever as the second graph is a psd I don't know how to hook the psdinput data to the xaxis of the first graph.
Thanks
Ste

from __future__ import division

from matplotlib.lines import Line2D
import time, operator

cline = Line2D((0,1),(0,1))
cline_on = False
lastxdata = 0
lastydata = 0
myAxis = None
lastXstart = 0
lastXend = 0

def on_move( event ):
    global cline, cline_on
    global lastxdata, lastydata
    x,y = event.x, event.y
    if event.button == 2 and event.inaxes:
        print "===================================================="
        print 'data co-ords x=%f, y=%f' %(event.xdata, event.ydata)
        print "   X diff = %f" %(event.xdata -lastxdata) 
        print "   Y diff = %f" %(event.ydata -lastydata) 
        lastxdata = event.xdata
        lastydata = event.ydata
        if cline_on == True:
            cline_on = False
            cline.set_marker('')
            #print "Markers are disabled"
        else:
            cline_on = True
            cline.set_marker('o')
            cline.set_markeredgecolor('r')
            cline.set_markerfacecolor('y')
            cline.set_markersize(5)
            #print "Markers are enabled"
        event.canvas.draw()

def RecalcPowerSpectrum( event ):  
    global myAxis
    global lastXstart
    global lastXend
    xlim = myAxis.get_xlim()
    xstart = int(xlim[0])
    xend = int(xlim[1])
    if xstart != lastXstart or xend != lastXend:
        print '%s event detected, re-calc power spectrum' % event.name
        lastXstart, lastXend = xstart, xend
        lastXlimits = xlim
        print 'xlim1 =', xstart
        print 'xlim2 =', xend
        Fs = 2 * targetvel
        pylab.cla()
        fftdata = pylab.psd(vel[2*xstart:2*xend], NFFT=256, Fs=Fs, 
detrend=pylab.mlab.detrend_linear, window=pylab.mlab.window_hanning, noverlap=0)
    
def plotscandata(fin, yaxis):
    global nums
    global myAxis
    global vel
    global cline

    if 'numpy' in numerix.version:
        nums = 'numpy'
    if 'numarray' in  numerix.version:
        nums = 'numarray'
 
    print 'Opening file and loading array .'
    if nums == 'numarray':
        X= numerix.array(pylab.load(fin), type=pylab.UInt32)
    else: #numpy
        X= numerix.array(pylab.load(fin), dtype=pylab.UInt32)

    print 'Removing phase indicator(lsb)...'
    vel = X >> 1; #divide the array by 2 (lsb is phase marker)

    print "De-Interlacing data ............"
    #change single array into two colomn array (phase0, phase1)
    phase = numerix.reshape(vel, (-1,2))
    #Change the colomn array into a 2 row array
    swapped = numerix.swapaxes(phase,0,1)

    #convert period to freq
    pswapped0 = 100e6/swapped[0]
    pswapped1 = 100e6/swapped[1]


    print "Adding Phase0 and Phase 1 ......"
    combinedperiod = (swapped[0] + swapped[1])
    combined = 100e6/combinedperiod

#===============================================
    print "Starting plot ..................",
    legendText = []

    p1 = pylab.subplot(2,1,1) #first graph of 2 graphs
#    p1.xaxis.set_major_formatter(EngrFormatter(0, False)) #can only be whole 
number, don't show decimal places
    r = pylab.plot(combined)
    legendText.append('Combined')
    
    cline = r[0]
    myAxis = p1

    pylab.connect ('button_press_event', on_move)
    
    from matplotlib.ticker import LinearLocator
    majorLocator = LinearLocator(10)
    p1.xaxis.set_major_locator(majorLocator)
#    p1.yaxis.set_major_formatter(EngrFormatter(2, False)) #two decimal places


    if targetvel > 0:
        target = targetvel #convert the target velocity to KHz
        limit = .002
        minuslimit = target * (1 + limit)
        pluslimit = target * ( 1 - limit)
        print '\ngoing to print %.1f%% target lines %d, %d, %d' % (limit*100, 
minuslimit, target, pluslimit)
        pylab.axhline( y=target, color='m', linestyle='--')
        pylab.axhline( y=pluslimit, color='y', linestyle='--')
        pylab.axhline( y=minuslimit, color='y', linestyle='--')

    title = "VelocityGram ("+fin +")"
    pylab.title((title))
    pylab.ylabel('Freq (Hz)')
    pylab.xlabel('Fringe of travel')        
    pylab.legend(legendText, loc='lower right')

    pylab.subplot(2,1,2)
    Fs = 2 * targetvel
    fftdata = pylab.psd(vel, NFFT=256, Fs=Fs, 
detrend=pylab.mlab.detrend_linear, window=pylab.mlab.window_hanning, noverlap=0)
    pylab.connect( 'button_release_event', RecalcPowerSpectrum)
    pylab.show()
    
    

if __name__ == '__main__':
    import getopt
    import os
    import sys


    usage = '''Plot Velocity Gram of Vortex Instrument.
Usage:
    python velplot.py [options] [inputfile]

Arguments:
    inputfile                   name of scandata file to plot.
                                If omitted then input is scandata.log in 
current directory

Options:
    -h, --help                  this help message.
'''

    bin = 1
    fin = 'fake25Khz.log'
    targetvel = 25000
    
    try:
        opts, args = getopt.getopt(sys.argv[1:], "h",[])

        for o, a in opts:
            if o in ("-h", "--help"):
                print usage
                sys.exit(0)

        if len(args) > 1:
            raise getopt.GetoptError, 'Too many arguments'


    except getopt.GetoptError, msg:
        print msg
        print '\n', usage
        sys.exit(2)

    if len(args) > 0:
        fin = args[0]

    if not os.path.isfile(fin):
        print "File not found", fin
        sys.exit(1)

    from matplotlib import pylab , numerix
    plotscandata(fin, 'dummy')

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Re: [Matplotlib-users] trig plot from event?

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