friedrich python 7

8/12/2019 Friedrich Python 7

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Adapted from Richard P. Muller 1

Python GUIs (Graphical User Interfaces)Python GUIs (Graphical User Interfaces)

• Tkinter

– Python's de-facto standard GUI

– this is the only GUI we will cover

• WxWindows– supports Windows and MacOS; on Unix variants, it supports

both GTk+ and Motif toolkits

• Qt toolkit (PyQt), for KDE (PyKDE)

– Note: QT designer: powerful graphical GUI builder

• Gtk+ (used by Gnome)

• PyOpenGL: 3D applications

• ... and some others




Tk OverviewTk Overview

• Set of widgets designed by John K. Ousterhout, 1987• Tk == Tool Kit

• Mean to be driven by Tcl (Toolkit Control Language)

– Many people find Tcl limited

– Can also drive Tk with Perl, Python

• Tkinter is the Python Tk Interface

– Very easy to use




Hello, WorldHello, World

from Tkinter import *

w=Label(text="Hello, World!")

w.pack()

w.mainloop()

• Label() defines a label to be displayed

– text= specifies a parameter to be passed in

• pack() resizes the window to the proper size

• mainloop() enters the event loop, and the program idles

until a button is pushed, a menu is pulled, etc. It has to

idle until the program is killed, since we didn't define anyevents.




Events (Hello, Goodbye)Events (Hello, Goodbye)


w=Label(text="Hello, World").pack()

b=Button(text="Goodbye",command='exit').pack()

mainloop()

• Button label defined by text parameter

• Button defines a callback function, something to run

when it is pushed.

• Now mainloop() has an event to catch, so when we push

the button, mainloop() executes the exit command.




WidgetsWidgets

• Button

– A simple button, used to execute a command or other operation.

• Canvas

– Structured graphics. This widget can be used to draw graphs and

plots, create graphics editors, and to implement custom widgets.

• Checkbutton

– Represents a variable that can have two distinct values. Clicking

the button toggles between the values.

• Entry– A text entry field.

• Frame

– A container widget. The frame can have a border and a

background, and is used to group other widgets when creating ana lication or dialo la out.ars all other radiobuttons associated




Widgets (cont.)Widgets (cont.)

• Radiobutton

– Represents one value of a variable that can have one of many

values. Clicking the button sets the variable to that value, and

clears all other radiobuttons associated with the same variable.

• Scale

– Allows you to set a numerical value by dragging a "slider".

• Scrollbar

– Standard scrollbars for use with canvas, entry, listbox, and text

widgets.

• Text

– Formatted text display. Allows you to display and edit text with

various styles and attributes. Also supports embedded images

and windows.




Typical widgetsTypical widgets

Menu barLabel

Text area (for geometry input)

Text entry

Radio buttons

Checkbox




Dialog boxesDialog boxes

• Convenient way to get feedback from a user

– Confirm quit

– Inputs data directly into program

– Here 0 is returned for Yes, and 1 is returned for No




Simple Dialog Box ExampleSimple Dialog Box Example

import sys


from Dialog import *

def confirm_quit():

d = Dialog(None, title="Goodbye?",

text="Really Leave?", default=0,

bitmap=DIALOG_ICON, strings=("Yes","No"))

if d.num ==0:sys.exit()

return

l = Label(text="Hello, World!").pack()

b = Button(text="Goodbye",

command=confirm_quit).pack()

mainloop()




File Browser DialogFile Browser Dialog




File Dialog Example CodeFile Dialog Example Code

From Tkinter import *

from tkFileDialog import *

root = Tk()

– Set up the dialog box

filename=askopenfilename()

print filename




Menu Example CodeMenu Example Code


root = Tk()

menubar = Menu(root)

root.config(menu=menubar)

filemenu = Menu(menubar)

menubar.add_cascade(label='File',menu=filemenu)

def doPrint(): print 'doPrint'

filemenu.add_command(label='Print',

command=doPrint)

root.mainloop()




Exercises (II)Exercises (II)

• Numeric and Plotting:

– Create several functions, plot them and their FFT:

periodic functions

gaussians

step

– Add noise

– Do the same with two-dimensional functions




Exercises (III)Exercises (III)

• Astronomical application: Boltzmann plots

– Read in measured line intensities and transition parameters

– Calculate: Nupper/g = 1.66983E17*Tdv/freq/mu2S

– Plot log(Nupper/g) versus upper Energy

– Do a linear fit to get the temperature and column density

– Add a small GUI

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