🌐 Mailman 3 May 2016 - Tutor - python.org

Scripting Calligra sheets with Python
by Jim Byrnes Jan. 31, 2022

Jan. 31, 2022

I am trying to script Calligra Sheets (formerly KSpread) with python. I have gotten some of the included example scripts to run so I know python scripting is running. I found the following snippet on their website: import KSpread sheet = KSpread.view().sheet() # swap text of B5 and C6 t1 = sheet.text("B5") t2 = sheet.text(6,3) sheet.setText("B5", t2) sheet.setText(6, 3, t1) # swap value of D7 and E8 v1 = sheet.value("D7") v2 = sheet.value(8,5) sheet.setValue("D7", v2) sheet.setValue(8, 5, v1) Error: 'str' object has no attribute 'text' File "file:///usr/share/kde4/apps/sheets/scripts/extensions/myswap.py", line 4, in <module> This error message appeared in a dialog box. I've taught myself some Python but I don't understand what is happening here. Shouldn't t1 be a sheet object? What would cause it to be a str instead? Thanks, Jim

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Desktop Notifications on Linux
by Dharmit Shah June 29, 2017

June 29, 2017

Hi all, I am trying to create a script that will go through the /var/log/secure file on a Linux system and provide desktop notifications for failed login attempts. Here is the code - http://pastebin.com/MXP8Yd91 And here's notification.py - http://pastebin.com/BhsSTP6H I am facing issue in the function "new_attempts_from_last". I am not able to raise a desktop notification from this function. It always fails with this traceback - http://pastebin.com/cgHMScv3 I see this error only when I try to raise a notification from the aforementioned function. If I run test examples under /usr/share/doc/notify-python/examples, it works just fine. Also, if I try to raise a notification from under if __name__ == "__main__":, it works without any issues. So I don't think there's any issue with OS's notification daemon. Running from python shell like below also works fine: In [1]: import notification In [2]: notification.notification("Hey") What am I missing or doing wrong here? If it matters, I am running Fedora 20, python 2.7 and Cinnamon desktop environment. For readability purposes, I have provided pastebin links. Let me know if this is not the correct way. Regards, Dharmit.

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Correct use of model-view-controller design pattern
by boB Stepp June 19, 2016

June 19, 2016

I am currently mulling over some information Alan passed along a while back on using the model-view-controller design pattern (Would 'architectural pattern' be a better choice of phrase?). I have been doing my usual online readings and there is enough variation in what I have read that I would like to post the simplest code I've been able to come up with and see if my understanding of MVC is correct. My current understanding is that the model contains program logic and the data which the program logic manipulates. The view is just the interface with which the user interacts. The controller ties things together, refreshing the view appropriately, receiving messages from the view when something there has been changed by the user, interrogating the model when needed, and receiving the model's results and refreshing the view appropriately. In my simple code to follow, I have the contents of three files, which I have named model.py, controller.py and view.py. controller.py starts program execution. My intent is to keep each of the three as independent of the others as I can manage, so that ideally, I could modify one of them and not need (or minimally need) to modify the other files. So, for instance, I would hope that I could change the command line view code to a GUI and avoid having to change model.py at all and hopefully have very few alterations to controller.py, though I am not certain I can achieve the ideal of no modifications to the controller. Disclaimer: While I tried to write my best Python possible, I did not go full-bore and filter input, add error handling, except incidentally in one else block. ------------------------------------------------------------------------------------ controller.py: #!/usr/bin/env python3 '''Simple controller program to explore the model-view-controller design pattern.''' import sys import model import view def main(): '''Start and run the program.''' option_num = view.main_menu() while True: if option_num == '1': diameter = float(view.diameter_prompt()) circumf = model.circumference(diameter) view.display_circumference(str(diameter), str(circumf)) option_num = view.main_menu() elif option_num == '2': view.display_exit_msg() sys.exit() else: title = 'WARNING!\n' msg = ('That is not a valid option number.\nPlease enter a valid ' + 'number and press <Enter>.') view.display_msg(title, msg) option_num = view.main_menu() if __name__ == '__main__': main() ------------------------------------------------------------------------------------ model.py: #!/usr/bin/env python3 '''Simple 'model' program to explore the model-view-controller design pattern. ''' import math PI = math.pi def circumference(diameter): '''Calculate the circumference of a circle given its diameter.''' return PI * diameter ------------------------------------------------------------------------------------ view.py: #!/usr/bin/env python3 '''Simple view program to explore the model-view-controller design pattern.''' def main_menu(): '''Display main menu of options and return entered option number.''' print(''' Option 1: Calculate the circumference of a circle. Option 2: Exit this program. ''') main_menu_option = input('Enter an option number: ') return main_menu_option def diameter_prompt(): '''Display a prompt to enter a diameter and return that value.''' print() diameter = input('Enter a diameter: ') return diameter def display_circumference(diameter, circumference): '''Display the circumference calculated from the user-entered diameter.''' print() print('You entered a diameter of', diameter, '.') print('The circumference corresponding to that diameter is', circumference, '.') def display_exit_msg(): '''Display exiting the program message.''' print() print('Exiting this program...\n') def display_msg(title, msg): '''Display the passed title and message.''' print() print(title) print(msg) ------------------------------------------------------------------------------------ Does my code capture the essence of MVC? Am I misunderstanding anything or missing any nuances? Would this code scale upward as I would hope? That is, if I chose to add more options as to what could be done with the program, would I only need to add only the code for the new functionality and not have to rewrite any existing code? If I were to change from CLI to GUI, would this similarly mean only a rewrite of view.py without having to alter the other two files? Some other questions: 1) If I were to add code to filter user inputs, which file is the logical place to place such code? My current impression is that it should go in the controller, but I could see it being in the view. However, if I were to write a Validation class, I could see that as having uses beyond checking just user input. 2) Currently I am using a while loop in the controller to keep the view 'alive'. If I were to convert the view to a tkinter GUI, where would the root.mainloop() statement go? In the controller's main() method? What GUI-related stumbling blocks might I easily run into in going from CLI to GUI with this existing code? 3) If I were to add data files in place of (or in addition to) user input, in which aspect of MVC would file I/O be handled? I also welcome any Python-style critiques, including even the more nit picky ones. ~(:>) BTW, I did not attempt to write any classes as things seemed simple enough that functions seemed more appropriate and straightforward to me. If that is a bad choice, please let me know! TIA! -- boB

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Study Tips
by Steve Lett June 1, 2016

June 1, 2016

Hi folks, Just started learning python. I've been having a really hard time in getting started, and still am! I have a slight learning difficulty, including a stroke in Jan.2010. You wouldnt know even if u were here looking at me! Praise God for the great salvation! I have a slight learning difficulty. Has anyone got any tips on how to study programming and what approach would be best for me? Out of a long list of books that I have collected ( python, Blender, etc ) I have decided to start on Introducing Python (hard copy 2nd Ed, ebook 3rd ed) by Bill Lubanovic. Before that I was going to start with Python Programming for the Absolute Beginner, Michael Dawson. Any thoughts on these issues and especially the study tips already mentioned. Thank you, Steve

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Help with 'if' statement and the concept of None
by marat murad June 1, 2016

June 1, 2016

Hi I'm learning how to code with python an I have purchased the book 'Python Programming for the absolute beginner,third edition' by Michael Dawson. There is one concept that is confusing me in chapter 3 page 71 there is a program whose code I have pasted below. The author introduced a new way of coding the Boolean NOT operator with the 'if' statement I have highlighted the relevant area,apparently this if statement actually means if money != 0,which I understood,but the program below this one which introduces the idea of slicing also has a if statement similar to the first one,except the second one accepts 0 value but the first one doesn't. print("Welcome to the Chateau D'food") print("It seems we are quit full today.\n") money = int(input("How many dollars do you slip the Maitr D'? ")) *if money:* print("Ah I think I can make something work") else: print("Please sit ,it may be a while") input("\nPress enter to exit") The slicing program word = "existential" print("Enter the beginning and ending index for the word existential") print("press he enter key at 'Start' to exit") start= None while start != "": start=input("\nStart: ") * if start:* start=int(start) finish=int(input("Finish: ")) print ("word[",start, ":",finish, "]is " , end="") print(word[start:finish]) input("\nPress enter to exit") I hope i made sense. Thankyou

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Python OLS help
by Vadim Katsemba June 1, 2016

June 1, 2016

Hello there, I am having trouble running the Ordinary Least Squares (OLS) regression on Spyder. I typed in lm = smf.ols(formula='LATITUDE~DIAMETER',data=dataf).fit(), and I ended up getting this error: ValueError: For numerical factors, num_columns must be an int. How am I supposed to run the OLS, is there another module I need to use? Any help would be appreciated.

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Learning Regular Expressions
by Terry--gmail May 30, 2016

May 30, 2016

Running Linux Mint The YouTube Sentdex Video tutor I am following. He is working in Python3.4 and I am running Python3.4.3 He's demonstrating some Regular Expressions which I wanted to test out. On these test scripts, for future referrence, I have been putting my notes in Tripple Quotes and naming the scripts descriptively to be able to find them again, when I need to review. However, this time, when I copied in a simple script below my RE notes, and ran it from IDLE (and from Console) I got the following error: SyntaxError: EOF while scanning triple-quoted string literal Now, there was also a tripple-quoted string I had set a variable to in my script...so I thought it was the active part of the script! But eventually, through the process of elimination, I discovered the scripted worked great without the notes! I'd like to know what it is in the below Tripple-Quoted section that is causing me this problem...if anyone recognizes. In IDLE's script file..._it's all colored green_, which I thought meant Python was going to ignore everything between the tripple-quotes! But if I run just the below portion of the script in it's own file, I get the same While Scanning Tripple-Quotes error. #!/usr/bin/env python3 ''' Regular Expressions - or at least some Identifiers: \d any number \D anything but a number (digit) \s space \S anything but a space \w any character \W anything but a character . any character (or even a period itself if you use \.) except for a newline a search for just the letter 'a' \b the white space around words Modifiers {x} we are expecting "x" number of something {1, 3} we're expecting 1-3 in length of something -, so for digits we write \d{1-3} + means Match 1 or more ? means Match 0 or 1 * Match 0 or more $ Match the end of a string ^ Match the beginning of a string | Match either or - so you might write \d{1-3} | \w{5-6} [ ] a range or "variance" such as [A-Z] or [A-Za-z] Cap 1st letter followed by lower case or [1-5a-qA-Z] starts with a number inclusive of 1-5 then lower case letter then followed by any Cap letter! :) White Space Characters (may not be seen): \n new line \s space \t tab \e escape \f form feed \r return DON'T FORGET!: . + * ? [ ] $ ^ ( ) { } | \ if you really want to use these, you must escape them '\' ''' Thanks for your thoughts! --Terry

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Re: [Tutor] Learning Regular Expressions
by boB Stepp May 30, 2016

May 30, 2016

On Mon, May 30, 2016 at 12:13 PM, DirkJSoren(a)gmail.com <dirkjsoren(a)gmail.com> wrote: > Hi bob, > > I had used the wrong email address when I wrote to python tutor on this, and > evidently it > took a while for the monitors to let it go ahead and be entered in the list, > so I apologize > for the delay in my reply. That's okay. Note that Tutor is a collaborative learning environment, so that normally you should send your responses to the whole list, not just me. That way we can all learn from what is written. So I am sending this to the Tutor list, but not everything as I notice you sent another response with pretty much everything to Alan and Tutor. > I continued to mess with it, and it seems or appears that escape '\' was > being noticed by > the interpreter despite the fact it is in a triple quoted area! > > As for the traceback, (I am not sure what you mean by 'FULL TRACEBACK'), > there was no > highlighted point in the program. I simply got the message I printed here. I am back at home now with access to Python 3. What I meant was, if I have this Python file, test_traceback.py: #!/usr/bin/env python3 print('''I will deliberately use a backslash inside this triple-quote.\''') When I run this code from the command line, I get: Microsoft Windows [Version 6.1.7601] Copyright (c) 2009 Microsoft Corporation. All rights reserved. C:\Windows\system32>e: E:\>cd /py_projects E:\py_projects>py test_traceback.py File "test_traceback.py", line 5 ^ SyntaxError: EOF while scanning triple-quoted string literal This is what I mean by a full traceback. Notice it tells me what line of my code file where it first encountered a problem. Just so you have it in mind, with things involving quotes issues, the actual point of error might be several lines earlier. But in this case I kept things simple to illustrate the point. Now if you ran my one-line program in the Python interpreter, you would get a different kind of problem: Python 3.5.1 (v3.5.1:37a07cee5969, Dec 6 2015, 01:54:25) [MSC v.1900 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. py3: print('''I will deliberately use a backslash inside this triple-quote.\''') ... ... ... ... ... Notice that every time I hit return in the interpreter, trying to *run* the code, it would not do so. Instead, every time I press <Enter> I get three dots. This is because in my actual code it sees the second triple-quote as being two single-quotes and a parenthesis. It does not see the triple-quote as yet being completed, and, additionally, it does not see the print function as being closed. So if I do these completions, I get: py3: print('''I will deliberately use a backslash inside this triple-quote.\''') ... ... ... ... ... ' ... ... ... ''' ... ) I will deliberately use a backslash inside this triple-quote.''') ' py3: Notice the extra single-quote I threw in. I hope it shows in more detail what is going on. HTH! boB

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Adding tasks periodically to asyncio.get_event_loop().run_forever()
by An Nguyen May 30, 2016

May 30, 2016

Hello all, I have a question related to AsyncIO. I have a while True: loop that executes a list of tasks asynchronously every 10 seconds. while True: > loop = asyncio.get_event_loop() > tasks = [ ] > for arg in args: > tasks.append(asyncio.ensure_future(my_coroutine(arg))) > results = [ ] > results = loop.run_until_complete(gather(*tasks)) > print(results) > sleep(10) > Now how can I achieve the same outcome with loop.run_forever()? What I want to achieve is to have a loop.run_forever() in my main(). Then periodically, a list of tasks will be added to that event_loop for execution. Please enlighten me. Thank you. An.

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Logging exceptions, but getting stderr output instead
by Alex Hall May 30, 2016

May 30, 2016

Hello again list, I didn't expect to be back so soon. :) I'm trying to log my new script, and logger.info() works fine. However, logger.exception() doesn't; I see the exception print to stderr, and it never appears in the log. Oddly, info messages after that appear in the shell and in my log, whereas normally they are only in the log. Here's my logger setup: logger = logging.getLogger(appName) logger.setLevel(logging.DEBUG) infoLogFormatter = logging.Formatter("%(asctime)s\n%(name)s, %(levelname)s: %(message)s", datefmt = "%I:%M:%S %p, %B %d, %Y") infoLogFileName = appName+".log" infoFileHandler = logging.FileHandler(infoLogFileName, mode="w") infoFileHandler.level = logging.INFO infoFileHandler.setFormatter(infoLogFormatter) logger.addHandler(infoFileHandler) Then, I deliberately called a non-existant function: for rep in reps: try: workbook = xlsxwriter.Workbook(workbookName) worksheet = workbook.addWorksheet(rep.name) #should be add_worksheet, so this errors out except: logging.exception("Error generating spreadsheet for {name}".format(name= rep.name)) The string I pass to logging.exception, along with the stack trace, print to the command line and not to my log file. Other logging.info() calls also print to the command line, but they also appear in the log. I haven't done much with logging before, and what I have done has been debug only, never exceptions. The resolution to this will likely be obvious, but when I looked it up, I found only information about how to log exceptions. No one seems to have the problem of exceptions not being logged correctly. As a quick aside, is there an easy way to halt script execution for some exceptions? Right now, catching them means that execution continues, but I sometimes want to log the problem and then abort the script, as the error means it shouldn't continue. Thanks. -- Alex Hall Automatic Distributors, IT department ahall(a)autodist.com

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