小编Awa*_*rod的帖子

假设我有一个列表,
l = ['h','e','l','l','o']
我希望能够获取最后两个项目并使用它们,但我不知道列表有多长
(它是用户输入).所以不能这样做,l[3:]因为如果列表是七个(或任何数字)项长而不是五个？

我如何从列表的后面算起？

我有一些代码在窗口中显示一些小部件.但是小部件不会出现在窗口中:

#!/usr/bin/python
import sys
from PySide import QtGui

class Window(QtGui.QMainWindow):
  def __init__(self):
    super(Window,self).__init__()
    self.initUI()
  def initUI(self):
    self.setGeometry(200,500,400,400)
    self.setWindowTitle("A Grid Layout")
    l1 = QtGui.QLabel("Label 1")
    l2 = QtGui.QLabel("Label 2")
    l3 = QtGui.QLabel("Label 3")
    le1 = QtGui.QLineEdit()
    grid = QtGui.QGridLayout()
    grid.setSpacing(10)
    grid.addWidget(l1,1,0)#widget,row,column
    grid.addWidget(l2,2,1)
    grid.addWidget(l3,3,2)
    grid.addWidget(le1,4,0,1,2)#row,column span
    self.setLayout(grid)#sets layout
    self.show()

def main():
  app = QtGui.QApplication(sys.argv)
  win = Window()
  exit(app.exec_())

if __name__ == "__main__":
  main()

我是PySide布局的新手,所以非常感谢任何帮助.

我有一个小的Python程序,它获取Tkinter规模的值并将其放入标签中.

#!/usr/bin/python

from Tkinter import *

class App:

    strval = StringVar()
    def __init__(self,master):

        frame = Frame(master)
        frame.pack()
        self.slide = Scale(frame, command = self.up, from_ = 1, to = 100)
        self.out = Label(frame, textvariable = self.strval)
        self.slide.pack()
        self.out.pack()

    def up(self,newscale):
        amount = str(newscale)
        self.strval.set(amount)


root = Tk()
app =  App(root)
root.mainloop()

当我运行程序时,它给了我和错误消息:

Traceback (most recent call last):
  File "/Users/alex/Desktop/Python/Tkinter/scale_Entry.py", line 5, in <module>
    class App:
  File "/Users/alex/Desktop/Python/Tkinter/scale_Entry.py", line 7, in App
    strval = StringVar()
  File "/System/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/lib-tk/Tkinter.py", line 254, in __init__
    Variable.__init__(self, …