在windows下的虛擬環境中使用tk，要留神了

事情是這樣的：有朋友在學習用matplotlib作圖，遇到一些問題問我，我也沒用過，就想先裝一個試試。然后呢，我就隨手創建了個虛擬環境。結果，涉及到matplotlib的第一行就報錯了：

Traceback (most recent call last):
  File "D:/workspace/PyTest/get_data.py", line 22, in <module>
    plt.scatter(X[:50, 0], X[:50, 1], color="red", marker="o", label="setosa")
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 3420, in scatter
    ax = gca()
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 950, in gca
    return gcf().gca(**kwargs)
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 586, in gcf
    return figure()
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 535, in figure
    **kwargs)
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\backends\backend_tkagg.py", line 81, in new_figure_manager
    return new_figure_manager_given_figure(num, figure)
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\backends\backend_tkagg.py", line 89, in new_figure_manager_given_figure
    window = Tk.Tk()
  File "C:\Python35\Lib\tkinter\__init__.py", line 1868, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: Can't find a usable init.tcl in the following directories: C:/Python35/lib/tcl8.6 D:/workspace/PyTest/py3env/lib/tcl8.6 D:/workspace/PyTest/lib/tcl8.6 D:/workspace/PyTest/py3env/library D:/workspace/PyTest/library D:/workspace/PyTest/tcl8.6.4/library D:/workspace/tcl8.6.4/library This probably means that Tcl wasn't installed properly.

 

經過分析，我想這是因為沒有找到tkinter，而matplotlib需要用到這個。可是這東西裝python時候是默認的，我肯定會裝的。我翻了翻我的電腦，Tcl確實是裝了的：

 

可是路徑不對。經群里的同學指導，我還特意在主環境下測試了一下tk和tcl環境：

import tkinter
root = tkinter.Tk()
print(root.tk.exprstring('$tcl_library'))
print(root.tk.exprstring('$tk_library'))

 

在主環境中結果也是正常的：

C:\Python35\tcl\tcl8.6
C:/Python35/tcl/tk8.6

 

可是虛擬環境中就不正常了。

Traceback (most recent call last):
  File "D:/workspace/PyTest/testtk.py", line 2, in <module>
    root = tkinter.Tk()
  File "C:\Python35\Lib\tkinter\__init__.py", line 1868, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: Can't find a usable init.tcl in the following directories: 
    C:/Python35/lib/tcl8.6 D:/workspace/PyTest/py3env/lib/tcl8.6 D:/workspace/PyTest/lib/tcl8.6 D:/workspace/PyTest/py3env/library D:/workspace/PyTest/library D:/workspace/PyTest/tcl8.6.4/library D:/workspace/tcl8.6.4/library



This probably means that Tcl wasn't installed properly.

 

這可就尷尬了。

但是，我又注意到一個細節：Tcl在查找環境的時候，會查找本機的主python環境，比如剛才那段報錯中，Tcl查找了這樣兩個環境：

C:/Python35/lib/tcl8.6
D:/workspace/PyTest/py3env/lib/tcl8.6

 

其中C盤是我的主環境，D:/workspace/PyTest/py3env是虛擬環境。

然后我開始翻代碼，看tcl查詢的路徑是啥。找不到。網上介紹了添加環境變量，TCL_LIBRARY和TK_LIBRARY，我試了也不行（可能這兩個變量僅限於Linux系統），在path里面添加也不行。

走投無路的情況下我開始動歪腦筋，把Tcl8.6整個文件夾從C:\Python35\tcl\復制到了C:\Python35\Lib中，然后，居然……

Traceback (most recent call last):
  File "D:/workspace/PyTest/ML/mcpperceptron/get_data.py", line 22, in <module>
    plt.scatter(X[:50, 0], X[:50, 1], color="red", marker="o", label="setosa")
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 3420, in scatter
    ax = gca()
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 950, in gca
    return gcf().gca(**kwargs)
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 586, in gcf
    return figure()
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\pyplot.py", line 535, in figure
    **kwargs)
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\backends\backend_tkagg.py", line 81, in new_figure_manager
    return new_figure_manager_given_figure(num, figure)
  File "D:\workspace\PyTest\py3env\lib\site-packages\matplotlib\backends\backend_tkagg.py", line 89, in new_figure_manager_given_figure
    window = Tk.Tk()
  File "C:\Python35\Lib\tkinter\__init__.py", line 1868, in __init__
    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)
_tkinter.TclError: Can't find a usable tk.tcl in the following directories: 
    C:/Python35/lib/tcl8.6/tk8.6 C:/Python35/lib/tk8.6 D:/workspace/PyTest/py3env/lib/tk8.6 D:/workspace/PyTest/lib/tk8.6 D:/workspace/PyTest/py3env/library



This probably means that tk wasn't installed properly.

 

報的錯從“找不到Tcl”變成了“找不到Tk”！

難道說成功了？於是，我又如法炮制，把tk8.6文件夾從C:\Python35\tcl\復制到了C:\Python35\Lib\tcl8.6中。

然后就真的成功了！

 

這叫什么鬼問題嘛！╭(╯^╰)╮

好吧，就是提醒注意一下，在windows中的虛擬環境下，如果使用tk，注意tcl和tk的路徑。可以把整個目錄復制到tcl和tk的搜索路徑中。至於這叫什么操作，我也不知道。