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POHow to interactively find and annotate local max (peaks) in matplotlib?
 

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  1. POHow to interactively find and annotate local max (peaks) in matplotlib?
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    <p>I'm trying to analyze some spectra for finding spectroscopic peaks, I've writen this simple code to find the max Y value (the peak) between two X data by clicking before and after the peak that I want to find. This works and I can get the coordinate of the peak but I would like to automatically annotate the peak found.</p> <pre><code>import matplotlib.pyplot as plt X=[1,2,3,4,5,6,7,8,9,10] Y=[1,1,1,2,10,2,1,1,1,1] fig = plt.figure() ax = fig.add_subplot(111) ax.plot(X,Y,label="prova") #plot the function #plt.legend(loc=1, ncol=1, shadow=True) plt.xlim(min(X) * 0.9, max(X) * 1.1) plt.ylim(min(Y) * 0.9, max(Y) * 1.1) plt.ylabel(r'Y axis') plt.xlabel(r'X axis') Diz=dict(zip(X,Y)) #create a dictionary that associate X with Y Interval=[] #interval where the user search for peaks PeaksList=[] #list of peaks found def onclick(event): print 'First limit at =%f'%(event.xdata) Interval.append(event.xdata) if len(Interval)%2==0: a=Interval[-2] b=Interval[-1] if b&lt;a: #if the user select first the highest value these statements filp it! A=b B=a else: A=a B=b #find the max Y value: the peak! peakY=0 #max Y value piccoX=0 #value of the X associate to the peak for i in [ j for j in X if A&lt;j&lt;B] : if Diz[i]&gt;peakY: peakY=Diz[i] piccoX=i print "Interval: %f - %f Peak at: %f " %(a,b,piccoX) PeaksList.append([piccoX,peakY]) ax.annotate("picco", xy=(piccoX,peakY), xycoords='data', xytext=(-50, 30), textcoords='offset points', arrowprops=dict(arrowstyle="-&gt;") ) plt.show() cid = fig.canvas.mpl_connect('button_press_event', onclick) </code></pre> <p>This is what I would like to have after the second click: <img src="https://i.stack.imgur.com/0lEw6.png" alt="enter image description here"></p>
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    1. COdo you want the find and annotate all maxima?
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      1. POHow to interactively find and annotate local max (peaks) in matplotlib?
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    2. CO@Jakob I would like to annotate the peak I've found clicking before and after it how I've written in the question. Try the code for understand! Thanks.
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