🌐 Mailman 3 May 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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flatten a python list
by Manprit Singh June 1, 2021

June 1, 2021

Dear sir, consider a problem to get a flat list for below given list : lst = [[2, 6], [5, 8], [6, 0]] the flatten list will be : ans = [2, 6, 5, 8, 6, 0] I have seen in several texts around the internet and even in the textbooks, the approach followed is to use nested for loop. ans = [] for ele in lst: for num in ele: ans.append(num) instead of using this for loop if i write : ans = [] for ele in lst: ans.extend(ele) Although the answer is correct, I need your comments on this approach. Just for the sake of healthy discussion, i am putting this question Although i can do it in a very efficient manner with list comprehension as given below: ans = [num for ele in lst for num in ele] Regards Manprit Singh

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product of all arguments passed to function call
by Manprit Singh June 1, 2021

June 1, 2021

Dear sir , Consider a problem where i have to find the product of all arguments passed to function call , where the function must be capable of accepting any number of arguments : My approach will be as follows : def product(x, *y): for ele in y: x *= ele return x ans = product(3, 4, 2) print(ans) gives the right answer = 24 ans = product(3, 4, 2, 5) print(ans) gives the right answer = 120 The point here is, in both cases, 3 is the first argument which will be passed to formal parameter x, and rest of the arguments will be received by y in the form of tuple. Is my understanding correct? is my problem solving correct in this case ? Regards Manprit Singh

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to place all zeros of an existing list in the starting of a new list
by Manprit Singh May 31, 2021

May 31, 2021

Dear sir , Consider a list ls = [2, 5, 0, 9, 0, 8], now i have to generate a new list from this existing list , new list must contain all zeros in the starting, all other elements of the existing list must be placed after zeros in new list . So new list must be : new = [0, 0, 2, 5, 9, 8] The way I am doing it is : >>> ls = [2, 5, 0, 9, 0, 8] >>> sorted(ls, key=lambda x: x != 0) [0, 0, 2, 5, 9, 8] >>> Is this the correct way ? or is there something better that can be done ? Regards Manprit Singh

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Why does CPython cache small integers "asymmetrically"?
by boB Stepp May 29, 2021

May 29, 2021

I often wonder how Python design decisions are reached. I wish there was a single go-to place for these sorts of questions! I cannot resist asking why -- if anyone happens to know -- more positive integers are cached than negative ones: Python 3.9.5 (tags/v3.9.5:0a7dcbd, May 3 2021, 17:27:52) [MSC v.1928 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> x = 256 >>> y = 256 >>> id(x) 1176492272016 >>> id(y) 1176492272016 >>> x = 257 >>> y = 257 >>> id(x) 1176503075504 >>> id(y) 1176503075408 # So Python stops caching at 2**16 on the positive side. >>> x = -4 >>> y = -4 >>> id(x) 1176492075152 >>> id(y) 1176492075152 >>> x = -5 >>> x = -5 >>> id(x) 1176492075120 >>> id(y) 1176492075152 # But strangely (to me) stops at -2**2 on the negative side. >>> x = 0 >>> y = 0 >>> id(x) 1176492075280 # Just to check. ~(:>)) I suppose most people tend to stick with whole numbers. But nonetheless I find this a bit surprising that the negative numbers are second class in this regard! Cheers! boB

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Re: [Tutor] Python Scraping problem help
by Alan Gauld May 27, 2021

May 27, 2021

On 27/05/2021 17:33, Dennis Lee Bieber wrote: > difference will be that enumerate counts from 0 Unless you give it a different starting number: =================== class enumerate(object) | enumerate(iterable, start=0) | | Return an enumerate object. | | iterable | an object supporting iteration | | The enumerate object yields pairs containing a count (from start, which | defaults to zero) and a value yielded by the iterable argument. ================== >>> for n,v in enumerate([0,1,2,3],start=5): print(n,v) 5 0 6 1 7 2 8 3 -- 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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Python Error
by Patrik Fougere May 27, 2021

May 27, 2021

Hi, I'm in the infancy stage of creating a UI app and I'm still a beginner coder. I'm running into a couple of issues and I would love any input on how to fix it. The first issue was turning string data into datetime data (I found an answer on google). The next issue was a value error in regards to the input of the string data. I've attached the image to this email. If you have any questions or advice please do not hesitate to reach out to me. Thank you. Please see the link below: https://www.online-python.com/xaytwZFliC - Patrik Fougere "Action is the foundational key to all success - Pablo Picasso"

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Python Scraping problem help
by CPECC张涛 May 27, 2021

May 27, 2021

Dear sir : Could you please help solve the below problem that can run but no result ,the program is runing,but can noly retrieve one picture ,Could you help tell me how to solve this problem . import requests from bs4 import BeautifulSoup import urllib import time,os headers={'User-Agent': 'Mozilla/5.0 (Windows NT 6.1;' 'Win64; x64) AppleWebKit/537.36 (KHTML, like' 'Gecko) Chrome/69.0.3497.100' 'Safari/537.36','Referer': "https://www.douban.com/group/topic/206388806/?type=rec"} url=r'https://www.douban.com/group/topic/206388806/?type=rec' wbdata=requests.get(url,headers=headers) # print(response) soup=BeautifulSoup(wbdata.content,'lxml') imgs=soup.select('div.image-wrapper>img') # print(imgs) number=1 for item in imgs: img=item.get('src') print(img) path=r'F:\Python crawler' if not os.path.isdir(path): os.makedirs(path) paths=path+str(number)+'.jpg' time.sleep(1) try: urllib.request.urlretrieve(img,paths) number+=1 # print('%sDownloaded'%img) except: continue

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Python Crawl problem help
by CPECC张涛 May 25, 2021

May 25, 2021

Dear sir : Could you please help solve the below problem that can not run and the result is "E:\Python Data Visualization\Scripts\python.exe" "E:/Python Data Visualization/爬虫/wallpaper2.py" None Traceback (most recent call last):   File "E:/Python Data Visualization/爬虫/wallpaper2.py", line 52, in <module>     start()   File "E:/Python Data Visualization/爬虫/wallpaper2.py", line 49, in start     imgs=getimgdata(page)   File "E:/Python Data Visualization/爬虫/wallpaper2.py", line 28, in getimgdata     for item in content_list.find_all('figure'): AttributeError: 'NoneType' object has no attribute 'find_all' Process finished with exit code 1 import requests import re import time import os from bs4 import BeautifulSoup import urllib def getpage(): url='https://www.zhihu.com/question/451014453/answer/1797338225' headers={'User-Agent': 'Mozilla/5.0 (Windows NT 6.1;' 'Win64; x64) AppleWebKit/537.36 (KHTML, like' 'Gecko) Chrome/69.0.3497.100' 'Safari/537.36','Referer': "https://www.zhihu.com" "/question/37787176"} try: r = requests.get(url, headers=headers).content return r except: return print('coneection error') def getimgdata(data): soup=BeautifulSoup(data,'lxml') content_list=soup.find('div',attrs={'class':'list'}) print(content_list) img_list=[] for item in content_list.find_all('figure'): img=item.find('img')['src'] img_list.append(img) return img_list def saveToDir(contents): img=40 try: path=r'F:\Python crawler' if not os.path.isdir(path): os.makedirs(path) img=0 for item in contents: paths=path+str(img)+'.jpg' time.sleep(1) urllib.request.urlretrieve(item,paths) img+=1 print('%sDownloaded'%img) except Exception as e: print(e) def start(): page=getpage() imgs=getimgdata(page) saveToDir(imgs) start()

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Expecting a float but get an int
by Phil May 24, 2021

May 24, 2021

Help please. This function returns "a" as .7 and "b" as 0 instead of .7. I'm sure the reason is obvious but I cannot see what it is. def slope_intercept(x1, x2, y1, y2): a = (y2 - y1) / (x2 - x1) # a = .7 which is correct #a = .7 b = (y1 - (a * x1) # b = 0 where it should be .7 return a, b slope, intercept = slope_intercept(9, 0, 7, 0) print("slope :", slope, "intercept :", intercept) This is what I've tried: a = float((y2 - y1) / (x2 - x1)) b = float((y1 - (a * x1)) In the function: x1 = float(x1) the same for x2, y1, y2 The debugger show "a" and "b" to be floats. The only way that I can have "b" show the correct answer is if I specifically make a = .7. What have I overlooked? -- Regards, Phil

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