🌐 Mailman 3 July 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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Labeling and Sorting a Test File
by Stephen P. Molnar July 30, 2021

July 30, 2021

First of all, let me say this is not a school exercise. I have a project that I am working on that is going to generate a large number of text files, perhaps in the thousands. The format of these files is: Detected 8 CPUs Reading input ... done. Setting up the scoring function ... done. Analyzing the binding site ... done. Using random seed: -596016 Performing search ... done. Refining results ... done. mode | affinity | dist from best mode | (kcal/mol) | rmsd l.b.| rmsd u.b. -----+------------+----------+---------- 1 -4.780168282 0.000 0.000 2 -4.767296818 8.730 11.993 3 -4.709057289 13.401 15.939 4 -4.677956834 8.271 11.344 5 -4.633563903 8.581 11.967 6 -4.569815226 4.730 8.233 7 -4.540149947 8.578 11.959 8 -4.515237403 8.096 10.215 9 -4.514233086 5.064 7.689 Writing output ... done. I have managed, through a combination of fruitlessly searching Google and making errors, this Python code (attached): #!/usr/bin/env python3 # -*- coding: utf-8 -*- import numpy as np with open("Ligand.list") as ligands_f: for line in ligands_f: ligand = line.strip() for num in range(1,11): #print(ligand) name_in = "{}.{}.log".format(ligand,num) data = np.genfromtxt(name_in,skip_header=28, skip_footer=1) name_s = ligand+'-BE' f = open(name_s, 'a') f.write(str(data[1,1])+'\n') f.close() The result of applying the code to ten files is: -4.709057289 -4.66850894 -4.747875776 -4.631865671 -4.661709186 -4.686041874 -4.632855261 -4.617575733 -4.734570162 -4.727217506 This is almost the way I want the file, with two problems: 1. I want to the first line in the textile to be the name of the file, in the example 'Test'. 2. I want the list sorted in the order of decreasing negative order: -4.747875776 -4.734570162 -4.727217506 -4.709057289 -4.686041874 -4.66850894 -4.661709186 -4.632855261 -4.631865671 -4.617575733 As my Python programming skills are limited, at best, I would appreciate some pointers in the right direction to implement the answers to my questions. Thanks in advance. -- Stephen P. Molnar, Ph.D. 614.312.7528 (c) Skype: smolnar1

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Acceleration of long lists
by Jan Kenin July 30, 2021

July 30, 2021

Hello, Often I append instances of objects in list-objects. Then I realize that the progress of my program slows down, when the list becomes larger and larger, e.g. larger than 3000. How can I accerlerate this? Perhaps it is a question of memory. Can I initialize the list in order to do the memory allocation only once? Thanks for all ideas! jankenin

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Re: [Tutor] Proper SQLite cursor handling?
by Alan Gauld July 29, 2021

July 29, 2021

On 28/07/2021 17:19, Dennis Lee Bieber wrote: > On Sun, 11 Jul 2021 18:34:01 -0400, Dennis Lee Bieber > Codd's opinion, NO field should allow NULL values. That implies that the > relevant fields are to be pulled out into a subordinate table, with a > unique foreign key to ensure that there are only 0 (the former NULL value) > or 1 record linked back to the parent record. That may be the purist view (or maybe just Codd!) but from a pragmatic view introducing new tables with a single value linked to from just one other table is a maintenance and performance nightmare. Plus it still begs the question about how you represent NULL values - thee are real world scenarios where things are optional and so can be NULL. You have to either invent spurious default values or some other way to fake it if using NOT NULL columns. > As a result, I've hacked my SQLite3 test scripts. One result is that > the BEFORE and AFTER UPDATE triggers are now gone -- the subordinate table > can have a default timestamp for datetime column, and NOT NULL will trap a > missing score. There may be a few cases where you are dealing with dynamic updates, but apart from simplistic databases like SQLite I still prefer writing a stored procedure or trigger to deal with those. > -- Doing this split does complicate the JOINs needed to retrieve data, > -- but also removed the need for UPDATE triggers to ensure end time > -- and score are filled in, as a default time can be specified, > -- and NOT NULL traps missing score. The avoidance of update triggers may cancel the performance penalty of the join. But it doesn't cancel the potential added complexity of all the selects, deletes, updates etc. which now have to manage two tables rather than one making them more fault prone. Its conceptually similar to the questions you must ask in OOP when determining when to create a new class for an attribute of an object. Does the added abstraction provide more benefit than the added complexity of maintaining two classes? Its the same debate with tables. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos

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OT: "Your tests are only as good as your mocks." Comments?
by boB Stepp July 26, 2021

July 26, 2021

From https://swizec.com/blog/what-i-learned-from-software-engineering-at-google/… The author of this article notes an example from his practice where his mock database that he used in his tests passed his tests when the actual code in production no longer had a database column that was in his mock database. As I have begun to play around with databases recently and how to test code relying on them, this really caught my attention. The overall article itself is a recap of what he read in a book about how Google does things ("Software Engineering at Google"). In this situation Google advocates for using "fakes" in place of mocks, where these fakes are simplified implementations of the real thing maintained by the same team to ensure API parity. How would the development and maintaining of these fakes be done so that the fakes don't drift from coding reality like the mocks might? It is not clear to me exactly what is going on here. And a more Python-specific question: Does the Python ecosystem provide tools for creating and managing fakes? -- Wishing you only the best, boB Stepp

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How to better understand args and kwargs
by Bhaskar Jha July 24, 2021

July 24, 2021

Hello, I am a newbie with Python. And, I want to understand what's the use of args and kwargs.. i understand that these are used when we do not know the number of arguments that will be passed.. but how is args different from kwargs.. and, why do we allow for a situation when someone can pass unlimited arguments to a function.. other languages such as C++ do not make provisions for this. So, why does Python do it? Kind Regards Bhaskar

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fixed quad
by Msd De July 24, 2021

July 24, 2021

I have nested integrals and need to use a fixed quad to carry out the integration Below is my code. Not sure of whether use of lambda function is appropriate need help with regards to use of lambda function. Thank you LB=0.0 UB=etatip K001_Intg=[None]*64;K0d1_Intg=[None]*64;Kd01_Intg=[None]*64;Kdd1_Intg=[None]*64 def kfac_11(eta,Ex): distGen=array_defl[i] a=2*FCON*abs(EL-Ex) ............... ............. ............ K001_Intg=F0_xp*Fd_xp*f_xp*etaTerm/W K0d1_Intg=Kdd_0*F0_xp**2*f_xp*etaTerm/W Kd01_Intg=K00_0*Fd_xp**2*f_xp*etaTerm/W Kdd1_Intg=F0_xp*Fd_xp*f_xp*etaTerm/W return [K001_Intg,K0d1_Intg,Kd01_Intg,Kdd1_Intg]; DFF_11=[] *def DEx11(Ex): * distGen=array_defl[i] global xp xp=(array_xefl[i,]) arr_KFact=[] *K_Fact=integrate.fixed_quad(kfac_11, LB, UB, args=(Ex, ), n=64) * ......... ......... ....... DEx_11=(ak2/ak1)*TP_1*DFF_11*CONST return DEx_11 JRuss11={} array_JRuss11=np.zeros(64) *for i in range(64): * *JRuss11[i]=integrate.fixed_quad(lambda Ex: DEx11(Ex),ELOW, EHIGH, n=64)* array_JRuss11[int(i)]=(JRuss11[i][0]) IntgRusscurr11=[] Russcurrent11=[] arr_Russcurrent11=np.zeros(64) *def currRuss11(xiRuss11): * IntgRusscurr11=array_JRuss11*np.sqrt(xiRuss11**2-etatip**2)*CCONST * return *IntgRusscurr11

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SYNTAX ERROR MESSAGE
by Chukwuemeka Ohakwe July 23, 2021

July 23, 2021

From random import randintdef pick(words): num_words = len(words) num_picked = randint(0, num_words - 1) word_picked = words[num_picked] return word_pickedprint(pick(name), pick(verb), 'a', pick(noun), end='.\n') Good day friends!please why does this program send error message when I run it? The error is highlighted at r in random. It reads: Syntax Error Invalid Syntax

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Set and get class members
by Phil July 21, 2021

July 21, 2021

I've read through several tutorial on this but I cannot relate what I'm reading to the problem. Say I wanted to set all the LED's status to false, or that of a particular LED, do I need a set function or can I access the attribute directly? In either case, what I have done below is not correct. class Led: def __init__(self, pos): self.pos = pos self.state def setState(self, s): self.state = s self.leds = list() for i in range(8): self.leds[i].setState(False) self.leds.append(Led((50 + (i * 30), 50))) -- Regards, Phil

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Re: [Tutor] object does not support item assignment
by Mats Wichmann July 19, 2021

July 19, 2021

On 7/19/21 10:22 AM, Dennis Lee Bieber wrote: > On Mon, 19 Jul 2021 12:54:07 +1000, Phil <phillor9(a)gmail.com> declaimed the > following: > > >> class Led: >> self.led = Led((50, 50)) > > How many Led classes do you have defined. To me, that assignment is > just creating another instance of the very class you have defined, and the > __init__() of that instance will define another instance, ad infinitum. what's more, because of the way Python evaluates things, at the time that line runs Led won't be defined yet, so you'll get a NameError. The class definition has to be fully executed before Python stores the object reference as the name Led.

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