【发布时间】：2019-12-20 13:52:25
【问题描述】：
我有一个 PyQt5 GUI 应用程序。这个应用程序显示了一个每秒更新的图表（使用我的默认xlim 和ylim），基本上是一个实时图表。我有这个功能，但我想添加一个NavigationToolbar，以便可以放大/缩小图表。
我将工具栏添加到我的布局中并显示出来。到现在为止还挺好。现在我放大，图表被放大，但是一旦图表定期更新，xlim 和ylim 再次默认并且缩放消失了。我需要从工具栏中调用哪些属性，以便保存它们并将它们传递给我的_update_canvas 函数？我查看了https://matplotlib.org/3.1.0/api/axes_api.html，并注意到了函数get_ylim。所以我尝试如下：
self._dynamic_ax.set_ylim(self._dynamic_ax.get_ylim()) 和 self._dynamic_ax.set_ylim(self._dynamic_ax2.get_ylim())
还有：
self._dynamic_ax.set_navigate(True)
但是这些都不起作用。如何保持NavigationToolbar设置的设置？不仅是缩放，还有平移。
一个最小的可运行代码示例：
import sys
from matplotlib.backends.qt_compat import QtCore, QtWidgets, QtGui
from matplotlib.backends.backend_qt5agg import (FigureCanvas, NavigationToolbar2QT as NavigationToolbar)
from matplotlib.figure import Figure
import matplotlib.pyplot as plt
buffer_size = 120
t = [t for t in range(buffer_size)]
bitthrough = [t for t in range(buffer_size)]
errors = bitthrough[::-1]
class App(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle("PCANbus sniffer")
self.table_widget = MyTableWidget(self)
self.setCentralWidget(self.table_widget)
self.setMinimumSize(QtCore.QSize(640, 400))
self.show()
class MyTableWidget(QtWidgets.QWidget):
def __init__(self, parent):
super(QtWidgets.QWidget, self).__init__(parent)
self.layout = QtWidgets.QVBoxLayout(self)
self.tabs = QtWidgets.QTabWidget()
self.tab_graph = QtWidgets.QWidget()
self.tab_info = QtWidgets.QWidget()
self.tabs.addTab(self.tab_graph, "PCANbus occupation")
self.tabs.addTab(self.tab_info, "PCANbus information")
self.tab_graph.layout = QtWidgets.QVBoxLayout(self)
self.dynamic_canvas = FigureCanvas(Figure(figsize=(6, 4)))
self.tab_graph.layout.addWidget(self.dynamic_canvas)
self.toolbar = NavigationToolbar(self.dynamic_canvas, self)
self.tab_graph.layout.addWidget(self.toolbar)
self._dynamic_ax = self.dynamic_canvas.figure.subplots()
self._dynamic_ax.set_xlabel("time (s)")
self._dynamic_ax.set_xlim(-5, 125)
self._dynamic_ax.set_ylabel("Throughput (%)", color="black")
self._dynamic_ax.set_ylim(-5, 120)
self._dynamic_ax.tick_params(axis="y", labelcolor="black")
# self._dynamic_ax.set_navigate(True)
self._dynamic_ax2 = self._dynamic_ax.twinx()
self._dynamic_ax2.set_ylabel("Errors (%)", color="blue")
self._dynamic_ax2.set_ylim(-4, 100)
self._dynamic_ax2.tick_params(axis="y", labelcolor="blue")
#self._dynamic_ax2.set_navigate(True)
self.tab_graph.setLayout(self.tab_graph.layout)
self.layout.addWidget(self.tabs)
self.setLayout(self.layout)
self.timer = QtCore.QTimer(self)
self.timer.timeout.connect(self._update_canvas)
self.timer.start(1000)
def _update_canvas(self):
self._dynamic_ax.clear()
self._dynamic_ax.plot(t, bitthrough, color="black")
self._dynamic_ax.set_xlabel("time (s)")
self._dynamic_ax.set_ylabel("Throughput (%)", color="black")
self._dynamic_ax.set_ylim(-5, 120) #self._dynamic_ax.get_ylim())
self._dynamic_ax.tick_params(axis="y", labelcolor="black")
self._dynamic_ax2.clear()
self._dynamic_ax2.plot(t, errors, color="blue")
self._dynamic_ax2.set_ylabel("Errors", color="blue")
self._dynamic_ax2.set_ylim(-4, 100) #self._dynamic_ax2.get_ylim())
self._dynamic_ax2.tick_params(axis="y", labelcolor="blue")
self._dynamic_ax.figure.canvas.draw_idle()
if __name__ == "__main__":
qapp = QtWidgets.QApplication(sys.argv)
app = App()
app.show()
qapp.exec_()
我真正的_update_canvas函数：
def _update_canvas(self):
wh_green = [a <= b for a, b in zip(bitthrough, llvl)]
wh_orange = [a > b and a <= c
for a, b, c in zip(bitthrough, llvl, lvl)]
wh_red = [a > b for a, b, in zip(bitthrough, lvl)]
# self._dynamic_ax.clear()
# self._dynamic_ax2.clear()
self._dynamic_ax.fill_between(
t, 0, bitthrough, where=wh_red, color="red", interpolate=True
)
self._dynamic_ax.fill_between(
t, 0, bitthrough, where=wh_orange, color="orange", interpolate=True
)
self._dynamic_ax.fill_between(
t, 0, bitthrough, where=wh_green, color="green", interpolate=True
)
# self._dynamic_ax.plot(t, bitthrough, color="black")
# self._dynamic_ax.set_xlabel("time (s)")
# self._dynamic_ax.set_ylabel("Throughput (%)", color="black")
# #self._dynamic_ax.set_ylim(self._dynamic_ax.get_ylim())
# self._dynamic_ax.tick_params(axis="y", labelcolor="black")
# self._dynamic_ax2.plot(t, errors, color="blue")
# self._dynamic_ax2.set_ylabel("Errors", color="blue")
# #self._dynamic_ax2.set_ylim(self._dynamic_ax2.get_ylim())
# self._dynamic_ax2.tick_params(axis="y", labelcolor="blue")
self._plot1.set_ydata(bitthrough)
self._plot2.set_ydata(errors)
# logging.debug("redrawing graph!!")
self._dynamic_ax.figure.canvas.draw_idle()
@DizietAsahi 的解决方案在使用fill_between 时不起作用。该区域被覆盖而不被清除。所以它们会重叠显示。
【问题讨论】：
标签： python matplotlib graph pyqt5