How to plot a line using Canvas/Matplotlib?

Question

I am trying to plot a line using canvas and matplotlib.

I already have the Figure, and everything else. But when i try to use the command to plot(self.axes.plot()) it does not work.

Does anyone knows what is happening?? Probably there is some detail that i am missing, but i can't find it!!

import sys
from PyQt5.QtWidgets import *
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
from matplotlib import pyplot as plt

class Window(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Plotting")
        self.setGeometry(50, 50, 700, 700)
        self.UI()
        self.show()

    def UI(self):
        # Cria o canvas para exibição dos entes da estrutura ------------------
        self.dpi = 70
        self.fig = Figure((5.0, 5.0), dpi=self.dpi, frameon=False, tight_layout=True)
        self.canvas = FigureCanvas(self.fig)
        self.axes = self.fig.add_subplot(111)

        # Cria grid de plotagem (axes) ----------------------------------------
        self.load_axes()

        layout = QGridLayout()

        layout.addWidget(self.canvas, 0, 0)

        self.setLayout(layout)

        self.plotar()

    def plotar(self):
        self.axes.clear()
        self.load_axes()
        self.axes.plot([0, 0], [1, 1], linestyle = '-', color = 'black', linewidth=5.5, zorder = 0)

        # Define a área de plotagem -------------------------------------------
        self.axes.relim()
        # Plota todas as linhas no canvas -------------------------------------
        self.fig.canvas.draw()

    def load_axes(self):
        self.axes.axis('equal')
        self.axes.set_xmargin(.4)
        self.axes.set_ymargin(.4)
        self.axes.autoscale_view(tight=True)
        self.axes.xaxis.set_major_locator(plt.MultipleLocator(5.0))
        self.axes.xaxis.set_minor_locator(plt.MultipleLocator(1.0))
        self.axes.yaxis.set_major_locator(plt.MultipleLocator(5.0))
        self.axes.yaxis.set_minor_locator(plt.MultipleLocator(1.0))
        self.axes.grid(which='major', axis='x', linewidth=0.75, linestyle='-', color='gainsboro')
        self.axes.grid(which='minor', axis='x', linewidth=0.50, linestyle='-', color='gainsboro')
        self.axes.grid(which='major', axis='y', linewidth=0.75, linestyle='-', color='gainsboro')
        self.axes.grid(which='minor', axis='y', linewidth=0.50, linestyle='-', color='gainsboro')


def main():
    App = QApplication(sys.argv)
    window = Window()
    sys.exit(App.exec_())

if __name__=='__main__':
    main()

Answer 1

It looks like it's actually drawing fine, no problem, but there is an issue with the ranges that you've specified for the axis.

You've specified: self.axes.plot([0, 0], [1, 1], linestyle = '-', color = 'black', linewidth=5.5, zorder = 0)

which means you're asking the x axis to display a range of 0 to 0 and the y axis to display 1 to 1. Try changing it to this:

self.axes.plot([0, 1], [0, 1], linestyle = '-', color = 'black', linewidth=5.5, zorder = 0)

That should display your line: :-D