Snippets
Revision 7 as of 2009-11-26 19:31:58
Clear message
1 #how to write text to a file (not safe)
2 open('foo.txt', 'w').write('hello')
3
4 #how to loop a certain number (e.g. 10) of times
5 for x in range(10):
6 print x
7
8 #how to concatenate a number and a string
9 x = 1
10 print str(x) + " is a string"
11 print "%s is a string" % x
12
13 #how to test if a string contains another string
14 my_string = "abcdef"
15 if "abc" in my_string:
16 has_abc = True
17
18 #check if an item is in a list or dictionary or tuple or set
19 my_list = [1, 2, 3, 4, 5]
20 if 1 in my_list:
21 has_one = True
22
23 my_dict = {"a": 1, "b": 2, "c": 3}
24 if "a" in my_dict:
25 has_a = True
26
27 # Lambda (anonymous functions)
28 add = lambda x, y: x + y
29 print add(3, 4) # prints "7"
30
31 # Reduce
32 from functools import reduce
33 def factorial(x):
34 return reduce(lambda accum, x: accum * x, range(1, x + 1), 1)
35
36 # Non-destructive sort on key
37 people = [ ... list of people objects ... ]
38 people_by_age = sorted(people, key=lambda person: person.age)
39
40 # Ternary expression (i.e. "BOOLEAN ? IF_TRUE : IF_FALSE")
41 print "a" if x == 1 else "b"
42 # Python 2.6 only!
43 # 2.5 or earlier: print (x == 1) and "a" or "b"
44
45
46 # Printing stuff nicely.
47 from pprint import pprint
48 pprint('Complex thing')
49
50
51 # generators/iteration
52 def generate_stuff ():
53 yield "x"
54 yield "y"
55 yield "z"
56
57 for item in generate_stuff ():
58 print item
59
60
61 #how to test if a string begins or ends with another string
62 my_string = "abcdef"
63 if my_string.startswith("abc"):
64 starts_with_abc = True
65 if my string.endswith("def"):
66 ends_with_def = True
67
68 #how to catch exceptions
69 grades = ['A', 'A-', 'B', 'C']
70 try:
71 grades.index("F")
72 except ValueError, inst:
73 #print out error info
74 print inst.args
75
76 # Catching multiple exceptions in Python.
77 try:
78 "do something"
79 except (ExceptionOne, ExceptionTwo):
80 # Note: The parens are important.
81 "handle the exception"
82
83 # Convert a file url to a file path in a shell script
84 deurledfile = `python -c 'import sys, urlparse, urllib; print urllib.unquote(urlparse.urlparse(sys.argv[1]).path)' $1`
85
86 # change/update value in a file with "="
87 try:
88 fin = file('file1', 'r')
89 fout = file(fin.name + '.new', 'w')
90 for line in fin:
91 fields = line.split('=') # Separate variable from value
92 if "keyname" == fields[0].strip():
93 line = "%s='%s'\n" % (fields[0], "newvalue")
94 fout.write(line)
95 fout.close()
96 fin.close()
97 os.rename(fout.name, fin.name)
98 except (OSError, IOError), e:
99 print("can't update the file")
100
101 # how to make money in open source
102 1. get developers
103 2. bzr commit
104 3.
105 4. profit
106
107 # how to generate pretty charts
108 # http://yokozar.org/blog/archives/48
109 import cairoplot
110
111 # Appears at the top of the chart produced at the end
112 chartTitle = "Simulated model of Wine development"
113 chartData = {"Working Apps" : [], "Happy Users" : []}
114 for x in xrange(100):
115 chartData["Working Apps"].append(float(x))
116 chartData["Happy Users"].append(float(x))
117 x_labels = [
118 "Project start", "25% bugs solved", "50% bugs solved",
119 "75% bugs solved", "All bugs solved"]
120 y_labels = ["0%", "25%", "50%", "75%", "100%"]
121 cairoplot.dot_line_plot(
122 "wine-model-results", chartData, 600, 600, x_labels = x_labels,
123 y_labels = y_labels, axis = True, grid = True,
124 x_title = chartTitle, y_title = "Percentage", series_legend=True )
125
126
127
128 #how to play a sound
129 import gst
130 player = gst.element_factory_make("playbin", "player")
131 player.set_property("uri", "file:///usr/share/sounds/ubuntu/stereo/bell.ogg")
132 player.set_state(gst.STATE_PLAYING)
133 # or
134 import pygame
135 pygame.mixer.init()
136 pygame.mixer.music.load("music.ogg")
137 pygame.mixer.music.play()
138
139
140 #notify-osd
141 import pynotify
142
143 n = pynotify.Notification("message name", "message", "icon")
144 n.show()
145
146 # more notify-osd stuff
147
148 # get the output of a command
149 import subprocess
150
151 date = subprocess.Popen(['date', '+%c'], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
152 (out, err) = date.communicate()
153 print 'exit code', date.returncode
154
155
156 #open a link in a web browser
157 import webbrowser
158
159 url = 'http://google.com/'
160 webbrowser.open_new(url)
161
162 #get the text for an html page from the web
163 import urllib
164 f = urllib.urlopen(day_url)
165 html = f.read()
166
167 #create a stock cancel button and pack it into the vbox
168 cancel_button = gtk.Button(stock=gtk.STOCK_CANCEL)
169 cancel_button.show()
170 cancel_button.connect("clicked", on_cancel_clicked)
171
172
173 # Parse XML file
174 import xml.dom
175 try:
176 dom = xml.dom.minidom.parseString(xml_content)
177 except ExpatError, e:
178 print >> sys.stderr, 'Invalid XML:', e
179
180 for p_node in dom.getElementsByTagName('p'):
181 print 'class of paragraph', p.attributes['class']
182 for child in p_node.childNodes:
183 print 'XML child node:', child
184
185
186 # search a file for a pattern and do something with every match
187 import re
188 for m in re.finditer('bug (\d+) blabla', text):
189 print 'bug number': m.match(1)
190
191
192 # download an URL and process it line by line
193 import urllib
194 for line in urllib.open('http://foo'):
195 print line
196
197
198 # grep all versioned files in a Bazaar tree
199 # Best command ever
200 bzr ls -VR --kind=file --null | xargs -0 grep -In <REGEX>
201 git grep <REGEX>
202
203
204 # Creating a Gtk+ TreeView:
205
206 # Instantiate the tree store and specify the data types
207 store = gtk.TreeStore(str, gtk.gdk.Pixbuf, int, bool)
208
209 # Create a TreeViewColumn
210 col = gtk.TreeViewColumn("File")
211 # Create a column cell to display text
212 col_cell_text = gtk.CellRendererText()
213 # Create a column cell to display an image
214 col_cell_img = gtk.CellRendererPixbuf()
215 # Add the cells to the column
216 col.pack_start(col_cell_img, False)
217 col.pack_start(col_cell_text, True)
218 # Bind the text cell to column 0 of the tree's model
219 col.add_attribute(col_cell_text, "text", 0)
220 # Bind the image cell to column 1 of the tree's model
221 col.add_attribute(col_cell_img, "pixbuf", 1)
222
223 col2 = gtk.TreeViewColumn("Size")
224 col2_cell_text = gtk.CellRendererText()
225 col2.pack_start(col2_cell_text)
226 col2.add_attribute(col2_cell_text, "text", 2)
227
228 # Create the TreeView and set our data store as the model
229 tree = gtk.TreeView(store)
230 # Append the columns to the TreeView
231 tree.append_column(col)
232 tree.append_column(col2)
233
234 #make a new ListStore when columns are calculated at runtim
235 col_count = 100
236 self.list_store = gtk.ListStore(
237 *[gobject.TYPE_STRING for i in range(col_count)])
238
239
240 #Put data into desktop CouchDB:
241
242 from desktopcouch.records.server import CouchDatabase
243 from desktopcouch.records.record import Record as CouchRecord
244
245 db = CouchDatabase("dbname", create=True)
246 record = CouchRecord(
247 {"a": 1, "b": 2}, record_type="http://recordtypeurl",
248 record_id=XXX)
249 db.put_record(record)
250
251 # Call a desktop CouchDB view:
252
253 view = """function(doc) { if (doc) emit(doc._id, doc); }"""
254 if not self.messages.view_exists("myview", "myapp"):
255 self.messages.add_view("myview", view, None, "myapp")
256 result = self.messages.execute_view("myview", "myapp")
257
258 #Creating a new Tomboy note
259 def create_tomboy_note(text):
260 bus = dbus.SessionBus()
261 obj = bus.get_object("org.gnome.Tomboy", "/org/gnome/Tomboy/RemoteControl")
262 tomboy = dbus.Interface(obj, "org.gnome.Tomboy.RemoteControl")
263
264 n = tomboy.CreateNote()
265 tomboy.DisplayNote(n)
266 tomboy.SetNoteContents(n, text)
267
268 #Set Pidgin status
269 def set_pidgin_status_text(message):
270 bus = dbus.SessionBus()
271 obj = bus.get_object("im.pidgin.purple.PurpleService", "/im/pidgin/purple/PurpleObject")
272 purple = dbus.Interface(obj, "im.pidgin.purple.PurpleInterface")
273
274 current = purple.PurpleSavedstatusGetType(purple.PurpleSavedstatusGetCurrent())
275 status = purple.PurpleSavedstatusNew("", current)
276 purple.PurpleSavedstatusSetMessage(status, message)
277 purple.PurpleSavedstatusActivate(status)
278
279 #How to embed a WebKit renderer in an application:
280 import gtk, webkit
281 gtk.gdk.threads_init()
282
283 window = gtk.Window()
284 window.connect("destroy", gtk.main_quit)
285 web = webkit.WebView()
286 web.open("http://ubuntu.com")
287
288 window.add(web)
289 window.show_all()
290 gtk.main()
291
292 # Put an icon in a Gtk+ text entry
293 GtkWidget *entry = gtk_entry_new();
294 gtk_entry_set_icon_from_stock(
295 GTK_ENTRY(entry), // specify which entry widget
296 GTK_ENTRY_ICON_SECONDARY, // put the icon at the end
297 GTK_STOCK_ABOUT); // make it display the "about" icon
298
299 # Display a progress bar in a Gtk+ entry
300 GtkWidget *entry = gtk_entry_new();
301 gtk_entry_set_text(GTK_ENTRY(entry), "This is a test");
302 gtk_entry_set_progress_fraction(GTK_ENTRY(entry), 0.5);
303
304 #Get Gtk+ theme colors
305 def get_theme_colors(w):
306 d = {}
307
308 for i in ["base", "text", "fg", "bg"]:
309 d[i] = Color.from_gtk_color(
310 getattr(w.get_style(), i)[gtk.STATE_NORMAL].to_string())
311
312 d["%s_selected" % i] = Color.from_gtk_color(
313 getattr(w.get_style(), i)[gtk.STATE_SELECTED].to_string())
314
315 return d
316
317 # Draw a rounded rectangle in Cairo
318 c = self.window.cairo_create()
319 x,y,w,h = w.allocation # x, y, width, height
320
321 c.move_to(x+r,y)
322 c.line_to(x+w-r,y); c.curve_to(x+w,y,x+w,y,x+w,y+r)
323 c.line_to(x+w,y+h-r); c.curve_to(x+w,y+h,x+w,y+h,x+w-r,y+h)
324 c.line_to(x+r,y+h); c.curve_to(x,y+h,x,y+h,x,y+h-r)
325 c.line_to(x,y+r); c.curve_to(x,y,x,y,x+r,y)
326 c.close_path()
327 c.fill()
328
329 # A Gtk+ label that supports text wrapping with fluid reflow
330
331 import gtk, pango, gobject
332
333 class WrapLabel(gtk.Frame):
334 def __init__(self, markup = None, text = None):
335 gtk.Frame.__init__(self)
336 self.set_shadow_type(gtk.SHADOW_NONE)
337
338 self.pango_layout = self.create_pango_layout(text or "")
339 if markup: self.pango_layout.set_markup(markup)
340 self.pango_layout.set_wrap(pango.WRAP_WORD_CHAR)
341
342 ev = gtk.EventBox()
343 ev.set_visible_window(False)
344 self.add(ev)
345
346 def do_expose_event(self, event):
347 gtk.Frame.do_expose_event(self, event)
348 self.set_size_request(-1, (self.pango_layout.get_size()[1] // pango.SCALE + 10))
349
350 x,y,w,h = self.allocation
351 gc = self.window.new_gc()
352 self.pango_layout.set_width(w * pango.SCALE)
353 self.window.draw_layout(gc, x, y, self.pango_layout)
354
355 gobject.type_register(WrapLabel)
356
357 w = gtk.Window()
358 w.connect("destroy", gtk.main_quit)
359
360 label = WrapLabel("This is a test")
361 w.add(label)
362
363 w.show_all()
364 gtk.main()
365
366 # Build a Gtk+ toolbar with UIManager
367 def on_action(action):
368 print "Action performed!"
369
370 actions = gtk.ActionGroup("Actions")
371 actions.add_actions([
372 ("bold", gtk.STOCK_BOLD, "_Bold", "<ctrl>B", None, on_action),
373 ("italic", gtk.STOCK_ITALIC, "_Italic", "<ctrl>I", None, on_action),
374 ("underline", gtk.STOCK_UNDERLINE, "_Underline", "<ctrl>U", None, on_action),
375 ])
376
377 ui_def = """
378 <toolbar name="toolbar_format">
379 <toolitem action="bold" />
380 <toolitem action="italic" />
381 <toolitem action="underline" />
382 </toolbar>
383 """
384
385 ui = gtk.UIManager()
386 ui.insert_action_group(actions)
387 ui.add_ui_from_string(ui_def)
388
389 vb = gtk.VBox()
390 vb.pack_start(ui.get_widget("/toolbar_format"), False)
391 vb.pack_start(editor, True)
392
393
394 # what to do instead of using eval() [this is safe security-wise]
395 import ast
396 ast.literal_eval ('[1,2,3,(4,5,6)]')
397
398 # How to use doctests well.
399 # Don't.
400
401 # getting your packages updated
402 # import os
403 # os.system('evolution mailto:seb128@debian.org?subject=hi')
404 # actually, he'll notice by himself.
405 from time import sleep
406 sleep (8 * 60 * 60) # go to bed
407
408 # How to set up a threaded GTK+ app
409 import pygtk
410 pygtk.require('2.0')
411 import gobject
412 import gtk
413
414 from threading import Thread
415
416
417 class Window(gtk.Window):
418 '''GtkWindow wrapper'''
419
420 def __init__(self):
421 gtk.Window.__init__(self)
422 self.set_title("Threaded GTK+ Sample")
423 self.set_default_size(320, 240)
424 Thread(target=self.timeout_thread).start()
425
426 def timeout_thread():
427 '''Threaded timeout demo'''
428 gtk.gdk.threads_enter()
429 self.show()
430 gtk.gdk_threads_leave()
431
432 if __name__ == "__main__":
433 gobject.threads_init()
434 gtk.gdk.threads_init()
435 try:
436 win = Window()
437 win.show()
438 gtk.gdk.threads_enter()
439 gtk.main()
440 gtk.gdk.threads_leave()
441 except KeyboardInterrupt:
442 gtk.main_quit()
443
444
445
446 #set the text on a pygtk widget in a Quickly app
447 widge = self.builder.get_object("object_name").set_text(my_string)
448
449 #get the text for a pygtk widdget in a Quickly app
450 self.builder.get_object("object_name").get_text(my_string)
451
452 #download an image from the web and save it
453 import urllib
454 img_stream = urllib.urlopen(url)
455 img_file = open(fname,'w')
456 img_file.write(img_stream.read())
457 del img_file
458
459
460 #download a large file using a read buffer, saves memory
461 import urllib
462 img_stream = urllib.urlopen(url)
463 img_file = open(fname,'w')
464 while 1:
465 buf = img_stream.read(4096)
466 if buf == "":
467 break
468 img_file.write(buf)
469 del img_file
470
471 # Still dealing with large files
472 # Compute the md5sum of a file without loading it all in memory
473 f = open(filepath)
474 digest = md5.new()
475 while 1:
476 buf = f.read(4096)
477 if buf == "":
478 break
479 digest.update(buf)
480 f.close()
481 print digest.hexdigest()
482
483
484
485 #how to use couchgrid and change the label of the column
486 from desktopcouch.records.couchgrid import CouchGrid
487 db="db name"
488 record_type="record type"
489 #the keys field is for to label the column and give a discription of what is in that column
490 keys=["key","another key"]
491 self.couchgrid=CouchGrid(db,record_type=record_type,keys=keys)
492 self.couchgrid.show()
493
494 #put the couchgrid into a vbox
495 self.builder.get_object("vbox1").pack_end(self.couchgrid)
496 self.couchgrid.editable=True
497
498 #change the name of the couchgrid column
499 couchgrid.get_column(0).set_title("some name")
500
501 #make the couchgrid column name dissapear
502 self.couchgrid.set_headers_visible (False)
503
504 #how to get stuff from a desktop couch db
505
506 from desktopcouch.records.server import CouchDatabase
507 from desktopcouch.records.record import Record
508
509 __couchdb = CouchDatabase("db name",create=True)
510 record_type="record type"
511 results = __couchdb.get_records(record_type=record_type,create_view=True)
512
513 #this takes the output of results and puts it into a string x
514 x=""
515 for r in results:
516 x+=r.value["key"]+" "
517
518 # PDB tip
519 pp locals()
520
521
522 # Parsing a line-based text file with separators
523 # Not that advanced, but I seem to have to write this all the time.
524
525 def parse_line(lines, separator):
526 for line in lines:
527 yield [token.strip() for token in line.split(separator)]
528
529 #create a pygtk window on the fly
530 test_window = gtk.Window(gtk.WINDOW_TOPLEVEL)
531 test_window.connect("destroy", gtk.main_quit)
532 test_window.set_title("my title")
533 test_window.set_default_size(200,75)
534 test_window.show()
535
536
537 # reading a bunch of stuff out of a function
538 total = []
539 for chunk in iter(lambda: file.read(4096), ''):
540 total.append(chunk)
541 result = ''.join(total)
542
543
544 # Transposing a list of lists.
545 zip(*list_of_lists)
546
547
548 # easy (if not efficient) sorted merging of two lists (works also for dicts)
549 l1 = [4, 5, 6]
550 l2 = [4, 6, 7]
551 for item in sorted(set(l1).union(l2)):
552 do_a_thing(item)
553
554
555 #add a message indicator
556 import indicate, time
557
558 def display(indicator):
559 print "Ah, my indicator has been displayed"
560
561 def server_display(server):
562 print "Ah, my server has been displayed"
563
564 server = indicate.indicate_server_ref_default()
565 server.set_type("message.im")
566 server.set_desktop_file("/usr/share/applications/empathy.desktop")
567 server.connect("server-display", server_display)
568 indicator = indicate.Indicator()
569 indicator.set_property("subtype", "im")
570 indicator.set_property("sender", "IM Client Test")
571 indicator.set_property_time("time", time.time())
572 indicator.show()
573 indicator.connect("user-display", display)
574
575
576 # post a microblog message using gwibber from karmic
577 bus = dbus.SessionBus()
578 db_mb_obj = bus.get_object("com.Gwibber", "/com/gwibber/Microblog")
579 microblog = dbus.Interface(db_mb_obj, "com.Gwibber")
580 import gwibber, gwibber.config
581
582 accounts = gwibber.config.Accounts()
583 args = ["This is a test message"]
584 for account in accounts:
585 if account["send_enabled"]:
586 acctid = account["id"]
587 microblog.operation({
588 "source": "lolz",
589 "id": "send-%s-%s" % (acctid, time.time()),
590 "accountid": acctid,
591 "args": args,
592 "opname": "send",
593 })
594
595
596 # post a microblog message using gwibber in lucid (not yet uploaded)
597 import gwibber.utils
598 foo = gwibber.utils.GwibberPublic()
599 foo.post("This is a test message")
600
601
602
603
604 # parse command line arguments
605 import optparse
606 op = optparse.OptionParser('%prog [options] inputfile')
607 op.add_option('-f', '--force', action='store_true', dest='force', default=False, help='Delete my files without asking')
608 op.add_option('-o', '--output-file', dest='outfile', help='Output file path; if not given, output to stdout')
609 (opts, args) = op.parse_args()
610 if opts.force:
611 print 'force enabled'
612 input_file = args[0]
613 if opts.outfile:
614 outfile = open(opts.outfile, 'w')
615 else:
616 outfile = sys.stdout
617
618
619 # SQLite
620 import sqlite3 as dbapi2
621 db = dbapi2.connect('mydb.sqlite')
622
623 cur1 = db.cursor()
624 cur1.execute('CREATE TABLE friends (name VARCHAR(255), phone int)')
625 cur1.commit()
626
627 cur1 = db.cursor()
628 cur1.execute('SELECT phone FROM friends WHERE name = ?', ['Fred']) # does proper quoting
629 for (phone) in cur1:
630 print 'Fred has telephone number', phone
631
632
633 # Apply file rights from src to dest
634 import os, stat
635 st = os.stat(src_file_name)
636 mode = stat.S_IMODE(st.st_mode)
637 os.chmod(dest_file_name, mode)
638
639
640
641 #translations using gettext
642 import gettext
643
644 #print hello world(it needs to be translated first though)
645 print gettext.gettext("hello")
646
647
648 # A really simple unittest module.
649
650 import unittest
651
652 class TestThing(unittest.TestCase):
653
654 def setUp(self):
655 super(unittest.TestCase, self).setUp()
656 self.data = [2, 3, 5]
657
658 def test_list_reversal(self):
659 backwards = reversed(self.data)
660 self.assertEqual([5, 3, 2], backwards)
661
662 def tearDown(self):
663 del self.data
664
665 # Note that you wouldn't really use setUp and tearDown for something this
666 # simple. Use them when you have something fairly complicated to set up.
667
668
669
670 # Look for a program that is already registered over dbus
671 import dbus
672 session_bus = dbus.SessionBus()
673 if session_bus.request_name ('net.soft.name') != 1:
674 print 'someone already has this name'
675 exit()
676
677 #open a file from a dialog
678 dialog = gtk.FileChooserDialog("Select a file", w, gtk.FILE_CHOOSER_ACTION_OPEN,
679 (gtk.STOCK_CANCEL, gtk.RESPONSE_CANCEL, gtk.STOCK_OPEN, gtk.RESPONSE_OK))
680
681 if dialog.run() == gtk.RESPONSE_OK:
682 fn = dialog.get_filename()
683 if os.path.exists(fn):
684 print fn
685 dialog.destroy()