Save Matplotlib subplot as PDF using PyFPDF

Question

I am trying to create two figures with two plots in each figure and then create a PDF file with one of the figures. I want to choose which figure will be saved in the PDF file. I have this simple code. It's just an example:

from fpdf import FPDF
from matplotlib import pyplot as plt
import tempfile
import io

# Examples
X = [0, 1, 2, 3, 4, 5, 6]
Y = [0, 1, 0, 1, 0, 1, 0]

X1 = [0, 1, 2, 3, 4, 6, 7, 8, 9, 10]
Y1 = [1, 4, 6, 4, 2, 12, 4, 6, 3, 12]

X2 = [0, 1, 2, 3, 4, 6, 7, 8, 9, 10]
Y2 = [1, 1, 1, 3, 6, 12, 18, 24, 30, 36]

X3 = [0, 1, 2, 3, 4, 6, 7, 8, 9, 10]
Y3 = [1, 30, 20, 30, 10, 30, 40, 40, 50, 20]


def plot(x,y, x1, y1):

    fig, (ax1, ax2) = plt.subplots(1, 2)
    ax1.plot(x, y)
    ax2.plot(x1, y1)

    return fig

def pdf_generator():

    fig = io.BytesIO()
    plt.savefig(fig, format="png")
    saved_fig = tempfile.NamedTemporaryFile()

    with open(f"{saved_fig.name}.png", 'wb') as sf:
        sf.write(fig.getvalue())

    pdf = FPDF('P', 'mm', 'A4')
    pdf.add_page(orientation='P', format='A4')
    pdf.set_xy(30, 50)
    pdf.image(fig, w=140, h=110)
    fig.close()

    return pdf.output('pdf_plot.pdf')

figA = plot(X1,Y1, X2,Y2)
figB = plot(X,Y, X3,Y3)

pdf_generator()

I created the figA and the figB. However, the figure that is always "converted" to PDF is the figB. I already tried to create a pdf_generator function that would accept as a parameter the figure's name but it didn't work.

Any suggestion to solve this problem?

Answer 1

You're nearly there, you just need to change your function definition to take as an argument the figure you want to plot, and save it using figure.savefig() rather than plt.savefig:

#...
def pdf_generator(figure):
    fig = io.BytesIO()
    figure.savefig(fig, format="png")
    #...

pdf_generator(figA)
pdf_generator(figB)