如果你在使用 Python 和 Matplotlib 时遇到无法绘图的问题，可能是由几个常见的原因引起的。以下是一些常见的问题及其解决方案：
1、 问题背景
在试图开发一个应用程序时，用户在输入值并按下按钮后，试图绘制图形，但是绘图失败。简化后的代码如下所示：
from numpy import arange, sin, pi
import matplotlib
matplotlib.use('WXAgg')
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigureCanvas
from matplotlib.backends.backend_wx import NavigationToolbar2Wx
from matplotlib.figure import Figure
import wx
class Input_Panel(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
# Input variables
self.button = wx.Button(self, label="Go")
# Set sizer for the panel content
self.sizer = wx.GridBagSizer(1, 1)
self.sizer.Add(self.button, (1, 2), (3, 6), flag=wx.EXPAND)
self.SetSizer(self.sizer)
class Output_Panel_Var(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
# Output variables
self.tittle = wx.StaticText(self, label="OUTPUTS:")
self.font = wx.Font(12, wx.DECORATIVE, wx.BOLD, wx.NORMAL)
self.tittle.SetFont(self.font)
self.lblt = wx.StaticText(self, label="t:")
self.resultt = wx.StaticText(self, label="", size=(100, -1))
self.lbls = wx.StaticText(self, label="s:")
self.results = wx.StaticText(self, label="", size=(100, -1))
# Set sizer for the panel content
self.sizer = wx.GridBagSizer(2, 2)
self.sizer.Add(self.tittle, (1, 3))
self.sizer.Add(self.lblt, (3, 1))
self.sizer.Add(self.resultt, (3, 2))
self.sizer.Add(self.lbls, (4, 1))
self.sizer.Add(self.results, (4, 2))
self.SetSizer(self.sizer)
class Output_Panel_Fig(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
self.figure = Figure()
self.axes = self.figure.add_subplot(111)
self.canvas = FigureCanvas(self, -1, self.figure)
self.sizer = wx.BoxSizer(wx.VERTICAL)
self.sizer.Add(self.canvas, 1, wx.LEFT | wx.TOP | wx.GROW)
self.SetSizer(self.sizer)
def draw(self,t,s):
self.axes.plot(t, s)
class Main_Window(wx.Frame):
def __init__(self, parent, title):
wx.Frame.__init__(self, parent, title = title, pos = (0, 0), size = wx.DisplaySize())
# Set variable panels
self.main_splitter = wx.SplitterWindow(self)
self.out_splitter = wx.SplitterWindow(self.main_splitter)
self.inputpanel = Input_Panel(self.main_splitter)
self.inputpanel.SetBackgroundColour('#c4c4ff')
self.outputpanelvar = Output_Panel_Var(self.out_splitter)
self.outputpanelvar.SetBackgroundColour('#c2f1f5')
self.outputpanelfig = Output_Panel_Fig(self.out_splitter)
self.main_splitter.SplitVertically(self.inputpanel, self.out_splitter)
self.out_splitter.SplitHorizontally(self.outputpanelvar, self.outputpanelfig)
# Set event handlers
self.inputpanel.button.Bind(wx.EVT_BUTTON, self.OnButton)
def OnButton(self, e):
t = arange(0.0, 1.0, 0.01)
s = sin(2 * pi * t)
#self.outputpanelvar.resultt.SetLabel('%.5f' % t)
#self.outputpanelvar.resultt.SetLabel('%.5f' % s)
self.outputpanelfig.draw(t,s)
def main():
app = wx.App(False)
frame = Main_Window(None, "T-Matrix Codes GUI")
frame.Show()
app.MainLoop()
if __name__ == "__main__" :
main()
如果直接绘制 t 和 s 的值，则绘图正常，但在按下按钮后，绘图失败。
2、 解决方案
解决方案是在 Output_Panel_Fig 类中的 draw 方法中添加 self.canvas.draw()，以便在绘制完图形后刷新绘图面板。
class Output_Panel_Fig(wx.Panel):
def __init__(self, parent):
...
def draw(self,t,s):
self.axes.plot(t, s)
self.canvas.draw()
完整代码如下：
from numpy import arange, sin, pi
import matplotlib
matplotlib.use('WXAgg')
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigureCanvas
from matplotlib.backends.backend_wx import NavigationToolbar2Wx
from matplotlib.figure import Figure
import wx
class Input_Panel(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
# Input variables
self.button = wx.Button(self, label="Go")
# Set sizer for the panel content
self.sizer = wx.GridBagSizer(1, 1)
self.sizer.Add(self.button, (1, 2), (3, 6), flag=wx.EXPAND)
self.SetSizer(self.sizer)
class Output_Panel_Var(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
# Output variables
self.tittle = wx.StaticText(self, label="OUTPUTS:")
self.font = wx.Font(12, wx.DECORATIVE, wx.BOLD, wx.NORMAL)
self.tittle.SetFont(self.font)
self.lblt = wx.StaticText(self, label="t:")
self.resultt = wx.StaticText(self, label="", size=(100, -1))
self.lbls = wx.StaticText(self, label="s:")
self.results = wx.StaticText(self, label="", size=(100, -1))
# Set sizer for the panel content
self.sizer = wx.GridBagSizer(2, 2)
self.sizer.Add(self.tittle, (1, 3))
self.sizer.Add(self.lblt, (3, 1))
self.sizer.Add(self.resultt, (3, 2))
self.sizer.Add(self.lbls, (4, 1))
self.sizer.Add(self.results, (4, 2))
self.SetSizer(self.sizer)
class Output_Panel_Fig(wx.Panel):
def __init__(self, parent):
wx.Panel.__init__(self, parent)
self.figure = Figure()
self.axes = self.figure.add_subplot(111)
self.canvas = FigureCanvas(self, -1, self.figure)
self.sizer = wx.BoxSizer(wx.VERTICAL)
self.sizer.Add(self.canvas, 1, wx.LEFT | wx.TOP | wx.GROW)
self.SetSizer(self.sizer)
def draw(self,t,s):
self.axes.plot(t, s)
self.canvas.draw()
class Main_Window(wx.Frame):
def __init__(self, parent, title):
wx.Frame.__init__(self, parent, title = title, pos = (0, 0), size = wx.DisplaySize())
# Set variable panels
self.main_splitter = wx.SplitterWindow(self)
self.out_splitter = wx.SplitterWindow(self.main_splitter)
self.inputpanel = Input_Panel(self.main_splitter)
self.inputpanel.SetBackgroundColour('#c4
如果上述方法都不能解决问题，仔细检查运行代码时的错误消息。错误消息通常会提供为什么 Matplotlib 无法绘图的线索。你可以根据错误消息进行具体的 Google 搜索，查找解决方案。
如果在解决 Matplotlib 绘图问题时还有其他疑问，可以提供更具体的代码和错误信息，以便进一步诊断和解决问题。
