清理matplotlib队列，并保存大的pdf数字

Question

I need to save different plots in the same pdf file, using data from different files. I use this code that for each step open certain file analyze it using some function and save on the pdf file. My problem is that the queue of matplotlib increases and at the end if I say plt.show() I get back a huge number of different figures. I do not want this, I would like to clean the queue of maplotlib without seeing the plots.

The code that I use is:

mu=arange(0.01,20.,0.03)
info1=[]
info2=[]
for i in range(0,7):

    inf1=[]
    inf2=[]
    pathe = path +"%i/"%(i)

    nameplot= "time_traces_%d.pdf"%(i)

    pp=PdfPages(nameplot)

    for j in mu:

        filename="InfoDati_"+"%lf_"%(j)+"%d.txt"%(i)



        fil = pathe + filename

        data=loadtxt(fil)

        t=data[:,0]
        x=data[:,1]
        y=data[:,2]             # y, z should be the simulation, x the sin
        z=data[:,3]

        x=array(x)

        y=array(y)

        z=array(z)

        t=array(t)


        fig=filename

        fig=plt.figure()
        plt.plot(t,x,t,y,t,z)

        plt.xlim(0,500)
        pp.savefig(fig)

        pp.close()
        `

if now I enter plt.show() I have back million of figures.. I need to quit the queue of plt.plot, or something like this!

The big problem is that for a lot of plots, the queue becomes so big that everything crash and the terminal says 'Killed' and quit ipython.

thanks for the help!

Answer 1

I'm not sure if I understand the problem, but this part of your code suggests you're not sure about what you're doing, so this is probably where the error lies:

    fig=filename # useless

    fig=plt.figure() # you're creating a figure that you never destroy
    plt.plot(t,x,t,y,t,z)

    plt.xlim(0,500)
    pp.savefig(fig)

    pp.close() # this shouldn't be inside this loop

• There's no reason to assign filename to fig , since right in the next line you're assigning plt.figure() to the same variable
• When you use pp.close() , that closes the pdf file you're currently saving your images to. But you're doing that inside the loop, even though pp is created outside of it.
• This leads to the conclusion that you meant to append each image to the PDF file, then close the image you have open (before creating a new one in the next step of the loop). So you probably want to do plt.close(fig) instead.
• Since with the code you posted you're never closing these images you create, this would also explain why you have too many open images.

Try removing that extra line, moving pp.close() to somewhere after the loop, adding plt.close(fig) inside the loop and see if that fixes your problem.