🌐 Mailman 3 August 2021 - 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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Python Help
by Malik Fuller Aug. 26, 2021

Aug. 26, 2021

Hi, I am very new to the coding world and I am in need of a very basic crash course on the format of inserts and how to achieve certain results when coding in python. Any help would be greatly appreciated!

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beautiful soup raw text workarounds?
by nathan Smith Aug. 25, 2021

Aug. 25, 2021

Hi List, I'm using beautiful soup to pass a website which is all going well. I'm having problems though with getting it to include the raw text, that is to say, text not in any tag. I've done some Googling on this and it seems beautiful soup does not support the text outside of tags? Fair enough! I was wondering how I could work around this issue? For instance, is there like, tag.endpos next_tag.startpos so I could do raw-text=text[endpos:nextpos] I've included the web page below for reference so you can see what I mean. the thing I am stuck on is below h2. Nathan ' Website: <html> <head> <title>This is my website</title> </head> <body> <h1>Headings</h1> <p>Paragraphs and such.</p> <h2>Another heading.</h2> This text here doesn't <br/> want to show in bs. </body> </html>

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terminating driver instance prior to completion
by David Haan Aug. 25, 2021

Aug. 25, 2021

I have a driver written in Python by others that is used to move a stepper motor. The parameters of the driver calls for, among other things, the number of steps the motor needs to be moved. It can be from 1 to infinity. I also have a hardware interrupt available that will indicate when the device the motor is moving has reached its home position. I need to stop the driver at that point regardless of the number of steps it has processed. I create an instance of the driver and pass it appropriate values for its variables. Once the driver instance starts, it will not return to the main program until it has processed all the steps I passed in one of the instance variables. When the hardware interrupt fires, I want to terminate the driver code execution so it will return control immediately to the main program flow. My question is if there is a method to terminate the Python driver code instance. I really don't want to copy the driver code and modify it specifically for my own program if I don't have to. Any suggestions would be appreciated.

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A complex number class, making a class instance of same class inside one of its methods
by Manprit Singh Aug. 25, 2021

Aug. 25, 2021

Dear sir, I have written a class Complex_num, from which i can set the values of real and imaginary part of complex number(setvalue) , and compare the magnitude of two instances of this class(__gt__()) . Add real and imaginary parts of two instances of this class(__add__()) and print the values of instance objects with __str__(). class Complex_num: def __init__(self): self.real = 0 self.imag = 0 def setvalue(self, real, imag): self.real = real self.imag = imag def __gt__(self, com_num): c1 = (self.real**2 + self.imag**2)**0.5 c2 = (com_num.real**2 + com_num.imag**2)**0.5 return c1 > c2 def __add__(self, com_num): temp = Complex_num() rpart = self.real + com_num.real ipart = self.imag + com_num.imag temp.setvalue(rpart, ipart) return temp def __str__(self): sign ="+" if self.imag >= 0 else "" com = "("+str(self.real)+sign +str(self.imag)+"j)" return com x = Complex_num() x.setvalue(4, 1) y = Complex_num() y.setvalue(4, -5) print(x) - returns (4+1j) print(y) - returns (4-5j) x > y returns False print(x+y) returns (8-4j) The answers are correct , but i have a question : Can we call the class inside any method of the class ? If I need an instance object of the class inside one of the methods of the same class. In the above given class Complex_num, inside def__add__() , i have made an instance object temp, The idea is after finding the sum of real and imaginary parts of instance objects x & y inside __add__(), I have set the instance variables of the instance object temp with this sum of real and imaginary parts, returning this temp will cause print(x+y) to print the sum of real and imaginary parts of x& y.due to __str__(). Regards Manprit Singh

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Concept of multithreading
by Manprit Singh Aug. 24, 2021

Aug. 24, 2021

Dear sir, As far as I have gone through the literature available, i got to know that multithreading is used for concurrent subprocesses, Although they are not truly concurrent (appears to be concurrent) - like if i have two subprocesses, i can process them in a concurrent way using multithreading module(An Example -in that way if CPU is idle for one subprocess, second subprocess can take place at that time, This would same total execution time). For Example : import time import threading def sumoflist(seq): sum_no = 0 for num in seq: sum_no += num time.sleep(6) print("Sum of list",sum_no) def sumoftuple(seq): sum_no = 0 for num in seq: sum_no += num time.sleep(3) print("Sum of tuple",sum_no) Calling these two functions in a sequential manner will take a total time approx. 9 seconds, as delay of 6 second and 3 seconds is introduced in the functions. Now using threading module, with following code: t1 = threading.Thread(target=sumoflist, args=([1, 2, 3],)) t2 = threading.Thread(target=sumoftuple, args=((2, 4, 3),)) t1.start() t2.start() t1.join() t2.join() It will take less time, because one of the thread may utilize the CPU idle time of another thread . Is my understanding correct ? This can be treated as a very basic example of multithreading ? Although the threading module is used for IO bound processes. Regards Manprit Singh sumoflist([1, 2, 3]) sumoftuple((2, 4, 3))

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Fw: Why Pyto package not available yet ???
by Steeve Kerou Aug. 23, 2021

Aug. 23, 2021

Hi, Here is Pyto, the first animated character that help you Learn Python like you play video games Why not implement me on Python PyPI ??? Episode 1: Intro / Who is Pyto ? / The Idle World | Pytorial | | | | | | | | | | | Episode 1: Intro / Who is Pyto ? / The Idle World | Pytorial | | | Alan V.

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A question about None
by Phil Aug. 22, 2021

Aug. 22, 2021

The distance sensor outputs "None" if the distance is greater than can be measured and "None", of course cannot be compared. So I came up with the following which is not quite correct: while True if distance_sensor.get_distance_cm() is not None: if distance_sensor.get_distance_cm() > 20: motor_pair.set_default_speed(20) motor_pair.start() else: continue elif distance_sensor.get_distance_cm() is not None: if distance_sensor.get_distance_cm() < 20: motor_pair.set_default_speed(-20) motor_pair.start() else: continue The idea is that if "None" returned from the sensor then nothing will happen and the loop will continue until "None" is not returned. Can anyone see the error of my ways? -- Regards, Phil

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Need to discuss about a class that can be used to print number of vowels, consonants, uppercase and lowercase letters and spaces in a string
by Manprit Singh Aug. 20, 2021

Aug. 20, 2021

Dear sir, I have written below given program using a class that will print number of vowels, consonants, uppercase and lowercase letters and spaces in a string, provided string contains only alphabets and space class StringStats: def __init__(self): self.str_seq = None self.uppercase = None self.lowercase = None self.vowel = None self.consonants = None self.spaces = None def set_string(self, seq): self.str_seq = seq def count_uppercase(self): self.uppercase = sum(ch.isupper() for ch in self.str_seq) def count_lowercase(self): self.lowercase = sum(ch.islower() for ch in self.str_seq) def count_vowels(self): self.vowel = sum(ch in "AEIOUaeoiu" for ch in self.str_seq) def count_consonants(self): self.consonants = sum(ch not in "AEIOUaeoiu " for ch in self.str_seq) def count_space(self): self.spaces = self.str_seq.count(" ") def compute_stats(self): self.count_uppercase() self.count_lowercase() self.count_vowels() self.count_consonants() self.count_space() def show_stats(self): print("String is-", self.str_seq) print("Count of vowels-", self.vowel) print("Count of consonants-", self.consonants) print("Count of uppercase letters-", self.uppercase) print("Count of lowercase letters", self.lowercase) print("Count of spaces", self.spaces) s_seq = "Amar Singh" st1 = StringStats() st1.set_string(s_seq) st1.compute_stats() st1.show_stats() Gives the answer as below : String is- Amar Singh Count of vowels- 3 Count of consonants- 6 Count of uppercase letters- 2 Count of lowercase letters 7 Count of spaces 1 Just need your comments on this class against following points : 1) The way i have initialized all instance variables inside __init__(), later on assigning values to each instance variable in different methods . 2) I have made different methods to set each instance variable, can't all these instance variables be set in a single method ? 3) Any further improvement in the class Regards Manprit Singh

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Re: [Tutor] Need to discuss about a class that can be used to print number of vowels, consonants, uppercase and lowercase letters and spaces in a string
by rmlibre＠riseup.net Aug. 19, 2021

Aug. 19, 2021

I'd create sets of each category because they have handy methods for doing inclusion / exclusion, plus they were designed to be very efficient at checking for contained values. This will be faster than checking `char.isupper()` etc. for every letter and for each category. That sounds like O(c*l) complexity, which means the running time would scale with the product of both the number of categories & the length of the string. I agree with the other responder that properties would be helpful here, since you can do the calculations only when they are needed. This also means the calculations will need to be done every time the value is queried. For some problems, you might want to only do calculations when they are needed, but you also only want to do them once if they are needed multiple times. In that case, the built-in functools module has an lru_cache decorator which handles caching calculated method values. I'd also use the Counter class from the built-in collections module. It will take quick care of giving the raw counts of each character (even the one's you haven't prepared for e.g. punctuation, control chars). The built-in string module also seems helpful here. If you can find built-ins which have already solved some of the problem you're needing to solve, it's a good idea to try finding them -- they're there to make your life easier. StringStats seems like a reasonable name. Even though abbreviations, or otherwise shortened words, are generally discouraged by PEP8 and other style guides in names, "stats" is a common enough shortening IMHO. However, you may also consider StringAnalysis. The method names could also be more clear. If the name of the class is changed to StringAnalysis, then it becomes more evident that each method should indicate which kind of value is going to be returned, if any. In your case, a character count. Names are important for many reasons. A name like CharacterCounter could also work, and may obviate the role of each method. It's up to you, that's why they're called style guides. Resources for Naming: (https://www.youtube.com/watch?v=5cafjDPPtJ0) (https://www.youtube.com/watch?v=n0Ak6xtVXno) Finally, and kind of restating a previous point, your class will struggle to compute over very large strings. As well, saving the string in the instance, while necessary in some cases, should be avoided if isn't for a good reason. Every time a string is moved, passed as an argument or stored in a variable, then the string is copied over to this new location. This can lead to lots of simultaneous copies of the same data during the runtime of a program. If the string is very large, then this issue can become a big problem in memory overhead. Below I'm posting an example of how I might write a class to get this job done. Consider it MIT licensed. Best, rmlibre import string from collections import Counter from functools import lru_cache # See also https://docs.python.org/3/library/functools.html#functools.cached_property class StringAnalysis: """ Creates objects which calculate the number of varying kinds of characters in a given string. Usage example: string = "some string to be analyzed" string_analysis = StringAnalysis(string) print(string_analysis.lowercase_count) 22 print(string_analysis.whitespace_count) 4 """ _LETTERS = frozenset(string.ascii_letters) _LOWERCASE = frozenset(string.ascii_lowercase) _UPPERCASE = frozenset(string.ascii_uppercase) _WHITESPACE = frozenset(string.whitespace) _VOWELS = frozenset("AEIOUaeiou") _CONSONANTS = _LETTERS.difference(_VOWELS) def __init__(self, string: str): """ Saves memory by keeping only the count of each letter within the instance, avoiding the copying of the entire string. Analysis is done within the instance properties. """ self._raw_count = Counter(string) @property @lru_cache() def vowel_count(self): vowels = self._VOWELS.intersection(self._raw_count) return sum(self._raw_count[char] for char in vowels) @property @lru_cache() def consonant_count(self): consonants = self._CONSONANTS.intersection(self._raw_count) return sum(self._raw_count[char] for char in consonants) @property @lru_cache() def uppercase_count(self): uppercase = self._UPPERCASE.intersection(self._raw_count) return sum(self._raw_count[char] for char in uppercase) @property @lru_cache() def lowercase_count(self): lowercase = self._LOWERCASE.intersection(self._raw_count) return sum(self._raw_count[char] for char in lowercase) @property @lru_cache() def whitespace_count(self): whitespace = self._WHITESPACE.intersection(self._raw_count) return sum(self._raw_count[char] for char in whitespace) On 2021-08-18 09:05, tutor-request(a)python.org wrote: > Send Tutor mailing list submissions to > tutor(a)python.org > > To subscribe or unsubscribe via the World Wide Web, visit > https://mail.python.org/mailman/listinfo/tutor > or, via email, send a message with subject or body 'help' to > tutor-request(a)python.org > > You can reach the person managing the list at > tutor-owner(a)python.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Tutor digest..." > > Today's Topics: > > 1. exec('a=1') in functions (Jan Kenin) > 2. Need to discuss about a class that can be used to print > number of vowels, consonants, uppercase and lowercase letters and > spaces in a string (Manprit Singh) > 3. Re: Need to discuss about a class that can be used to print > number of vowels, consonants, uppercase and lowercase letters and > spaces in a string (dn) > 4. Re: exec('a=1') in functions (Peter Otten) > 5. Re: Need to discuss about a class that can be used to print > number of vowels, consonants, uppercase and lowercase letters and > spaces in a string (Alan Gauld) > > _______________________________________________ > Tutor maillist - Tutor(a)python.org > https://mail.python.org/mailman/listinfo/tutor

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