Mailman 3 April 2023 - Python-list

>>> %matplotlib inline results in SyntaxError: invalid syntax
by Mike S Dec. 25, 2023

Dec. 25, 2023

I have installed Python 3.4.4 on XPSP3 and am trying to work my way through this tutorial. A Complete Tutorial on Ridge and Lasso Regression in Python http://www.analyticsvidhya.com/blog/2016/01/complete-tutorial-ridge-lasso-r… In Step 2 "Why Penalize the Magnitude of Coefficients?" we are shown this code: #Importing libraries. The same will be used throughout the article. import numpy as np import pandas as pd import random import matplotlib.pyplot as plt %matplotlib inline I get an error on the last line. I am running this code in Idle Python 3.4.4 Shell... Python 3.4.4 (v3.4.4:737efcadf5a6, Dec 20 2015, 19:28:18) [MSC v.1600 32 bit (Intel)] on win32 Type "copyright", "credits" or "license()" for more information. >>> import numpy as np >>> import pandas as pd >>> import random >>> import matplotlib.pyplot as plt >>> %matplotlib inline SyntaxError: invalid syntax What am I doing wrong? Suggested reading? TIA, Mike

7 8

Re: How to add CC and BCC while sending mails using python
by akegb3＠gmail.com June 20, 2023

June 20, 2023

On Tuesday, September 30, 2008 8:00:16 AM UTC-8, Bernhard Walle wrote: > Hi, > > * cindy jones [2008-09-30 19:57]: > > > > Can someone tel me how to add cc's and bcc's while sending mails using > > python > > Following (tested) snippet should help: > > ------------------ 8< ------------------------------ > from smtplib import SMTP > from email.mime.image import MIMEImage > from email.mime.text import MIMEText > from email.mime.multipart import MIMEMultipart > > to = 'to_address(a)example.invalid' > cc = 'cc_address(a)example.invalid' > bcc = 'bcc_address(a)example.invalid' > > msg = MIMEMultipart() > msg['To'] = to > msg['Cc'] = cc > msg['From'] = 'bernhard(a)bwalle.de' > msg['Subject'] = 'Test' > text = MIMEText('Das ist ein Test') > text.add_header("Content-Disposition", "inline") > msg.attach(text) > > s = SMTP('test.smtp.relay') > s.sendmail(msg['From'], [to, cc, bcc], msg.as_string()) > s.quit() > ------------------ >8 ------------------------------ > > > Regards, > Bernhard Hello Bernhard, I've tried the above code and the bcc address does not receive the message, on the To & CC addresses receive it. Here are snippets from my code, perhaps something will stand out to you? to = 'ed(a)domain.gov' cc = 'ed(a)gmailmail.com' bcc = 'ed(a)home.net' msg = MIMEMultipart() msg['To'] = to msg['Cc'] = cc msg['Subject'] = 'My Subject text here' msg['From'] = 'edsboss(a)domain.gov' smtp = SMTP("smtpserver") smtp.ehlo() smtp.sendmail(msg['From'], [to, cc, bcc], msg.as_string()) Thanks in advance..hope you're still out there!! ~Ed

3 2

Multithreading? How?
by pozz May 13, 2023

May 13, 2023

I need to develop a Python application that is a sort of gateway between to networks: a "serial bus" network (think of a serial port or a USB connection) and a MQTT connection (in my case, it's AWS IoT service). On the bus, a proprietary protocol is implemented. From the bus, the app knows the status of the system (think of a simple ON/OFF status). The user can retrieve the status of the system through MQTT: it sends a message to read/status MQTT topic and receive back a message with the current status on read/status/reply MQTT topic. Of course, they are just examples. On the contrary, when the app detects a status change reported from the serial bus (think of a transition from ON to OFF), it sends a MQTT message. I'm thinking to split the application in three classes: Bus, App and IoT. Bus and IoT are also threads. The thread of Bus manages the serial protocol, while the thread of IoT manages MQTT connection with the broker (the server). However I don't know if it could be a good architecture. Suppone Bus thread receives a new status from the system. In the context of ThreadBus, the object Bus could call a method of App object: app.set_status(new_status_from_the_bus) In the App I have: class App(): .. def set_status(new_status): # Could be called from ThreadBus if new_status != self.new_status: self.new_status = new_status # Do some actions on status change def get_status(): # Could be called from ThreadIoT return self.status Of course, IoT object needs to know the current status of the system when a message is received from MQTT. So ThreadIoT could call app.get_status(). I think this architecture has some problems with race conditions or threads synchronization. What happens if IoT calls get_status() exactly when set_status() called by ThreadBus is executing? If status is a big data structure, set_status() could be interrupted by get_status() that could get a completely corrupted status, because it was only partly updated by set_status(). I know I can use locks or semaphores in get_status() and set_status(), but I don't know if this is a good approach. Consider that the system is complex, it isn't composed by a simple single status. It has many many parameters that are collected from the serial bus. Should I use a lock for every [get|set]_status(), [get|set]_dimensions(), [get|set]_battery_level(), [get|set]_mains_present(), and so on? Another possibility is to use a Queue for Bus and a Queue for IoT. So the set_status(new_status) called from Bus object will be transformed in a put in the queue: app_queue.put({"type": "new_status", "data": ...}) However how could be transformed the get_status() from IoT? How the return value (the current status) is real retrieved? class IoT(): .. def status_request_from_MQTT(): app_queue.put({"type": "get_status"}) # How to get the status to return? return current_status Should the app put the status on the same queue and should IoT waits for a new message in the Queue? def status_request_from_MQTT(): app_queue.put({"type": "get_status"}) try: current_status = app_queue.get(timeout=10) except Empty: # What to do? return current_status Again another approach is to avoid multi-threading at all and create a single "main loop" function that waits at the same time for incoming events on the serial bus and MQTT (how?). I don't know if this could be done in my case, because I'm using awscrt Python module and it works through callbacks that I think is called from another thread. Any suggestions on this architecture?

2 1

Python-pickle error
by charles wiewiora May 9, 2023

May 9, 2023

Hello, I am experincing problems with the pickle moducle the folowing code was working before, import pickle number=2 my_pickeld_object=pickle.dumps(number) print("this is my pickled object",{my_pickeld_object},) with open('file.pkl', 'rb') as file: number=pickle.load(file) my_unpickeled_object=pickle.loads(my_pickeld_object) print("this is my unpickeled object",{my_unpickeled_object},) but now i get error Traceback (most recent call last): File "C:\Users\lukwi\Desktop\python\tester2.py", line 5, in <module> with open('file.pkl', 'rb') as file: FileNotFoundError: [Errno 2] No such file or directory: 'file.pkl' im get this problem after this, a .pkl came into my Python script files i though this could be a spare file made from python becauce i was doing this first, import pickle number=2 my_pickeld_object=pickle.dumps(number) print("this is my pickled object",{my_pickeld_object},) with open('file.pkl', 'rb') as file: number=pickle.load(file) so i stupidly deleted the file do you know how to fix this? i reinstalled it but it didn't work this is on widnows and on version 3.11.3 on python thank you

3 2

Using loguru in a library
by Roy Hann May 2, 2023

May 2, 2023

Is there anyone using loguru (loguru 0.5.3 in my case) successfully in a library? In my __init__.py in mylib I do logger.disable('mylib') which definitely works. I don't get any more logging. I "pip install ." the library, then in mytest.py I do import mylib logger.enable('mylib') expecting that it would report any log messages above level DEBUG, just as it does when I don't disable logging. Unfortunately it doesn't have any effect; it doesn't report any logging from mylib. I have verified that __name__ is visible in the library and is 'mylib'. I would also have expected that logger.enable(None) would turn all the logging on everywhere but it seems not. I have probably misunderstood how logger.enable() is supposed to be used. Can anyone share a brief example? Roy

3 2

Re: How to 'ignore' an error in Python?
by Chris Green April 30, 2023

April 30, 2023

Chris Angelico <rosuav(a)gmail.com> wrote: > On Sat, 29 Apr 2023 at 14:27, Kushal Kumaran <kushal(a)locationd.net> wrote: > > > > On Fri, Apr 28 2023 at 04:55:41 PM, Chris Green <cl(a)isbd.net> wrote: > > > I'm sure I'm missing something obvious here but I can't see an elegant > > > way to do this. I want to create a directory, but if it exists it's > > > not an error and the code should just continue. > > > > > > So, I have:- > > > > > > for dirname in listofdirs: > > > try: > > > os.mkdir(dirname) > > > except FileExistsError: > > > # so what can I do here that says 'carry on regardless' > > > except: > > > # handle any other error, which is really an error > > > > > > # I want code here to execute whether or not dirname exists > > > > > > > > > Do I really have to use a finally: block? It feels rather clumsy. > > > > > > I suppose I could test if the directory exists before the os.mkdir() > > > but again that feels a bit clumsy somehow. > > > > > > I suppose also I could use os.mkdirs() with exist_ok=True but again > > > that feels vaguely wrong somehow. > > > > > > > Why does exist_ok=True feel wrong to you? This is exactly what it is > > there for. > > > > Using mkdirs when you only want to make one is inviting problems of > being subtly wrong, where it creates too many levels of directory. > Personally, I would just do: > > try: os.mkdir(dirname) > except FileExistsError: pass > > and not try to handle anything else at all. > Yes, OP here, that seems to me to be the 'right' way to do it. Basically I hadn't realised the effect of pass in a try block and that's why I asked the question originally. -- Chris Green ·

3 2

Re: How to 'ignore' an error in Python?
by jak April 30, 2023

April 30, 2023

Chris Angelico ha scritto: > Using mkdirs when you only want to make one is inviting problems of > being subtly wrong, where it creates too many levels of directory. > Personally, I would just do: Maybe I only say this because it has happened to me too many times but before ignoring the error in the 'except' branch, I would make sure that if the name exists it is a folder and not a file.

2 1

Re: How to 'ignore' an error in Python?
by jak April 30, 2023

April 30, 2023

Stefan Ram ha scritto: > jak <nospam(a)please.ty> writes: >> Maybe I only say this because it has happened to me too many times but >> before ignoring the error in the 'except' branch, I would make sure that >> if the name exists it is a folder and not a file. > > If the name exists and it is a file's name, this will be detected > by "mkdir( exist_ok=True )", and an object will be raised. Such > an object, indeed, usually should /not/ be ignored by the caller. > But there is no reason to deviate from the EAFP path. > > Maybe I expressed myself badly but I didn't mean to propose alternatives to the EAFP way but just to evaluate the possibility that it is not a folder.

2 1

How to 'ignore' an error in Python?
by Chris Green April 29, 2023

April 29, 2023

I'm sure I'm missing something obvious here but I can't see an elegant way to do this. I want to create a directory, but if it exists it's not an error and the code should just continue. So, I have:- for dirname in listofdirs: try: os.mkdir(dirname) except FileExistsError: # so what can I do here that says 'carry on regardless' except: # handle any other error, which is really an error # I want code here to execute whether or not dirname exists Do I really have to use a finally: block? It feels rather clumsy. I suppose I could test if the directory exists before the os.mkdir() but again that feels a bit clumsy somehow. I suppose also I could use os.mkdirs() with exist_ok=True but again that feels vaguely wrong somehow. -- Chris Green ·

7 8

Re: How to 'ignore' an error in Python?
by Chris Green April 29, 2023

April 29, 2023

Kushal Kumaran <kushal(a)locationd.net> wrote: > On Fri, Apr 28 2023 at 04:55:41 PM, Chris Green <cl(a)isbd.net> wrote: > > I'm sure I'm missing something obvious here but I can't see an elegant > > way to do this. I want to create a directory, but if it exists it's > > not an error and the code should just continue. > > > > So, I have:- > > > > for dirname in listofdirs: > > try: > > os.mkdir(dirname) > > except FileExistsError: > > # so what can I do here that says 'carry on regardless' > > except: > > # handle any other error, which is really an error > > > > # I want code here to execute whether or not dirname exists > > > > > > Do I really have to use a finally: block? It feels rather clumsy. > > > > I suppose I could test if the directory exists before the os.mkdir() > > but again that feels a bit clumsy somehow. > > > > I suppose also I could use os.mkdirs() with exist_ok=True but again > > that feels vaguely wrong somehow. > > > > Why does exist_ok=True feel wrong to you? This is exactly what it is > there for. > It was rather using os.mekedirs() to create a single directory that seemed wrong. If os.mkdir() had exist_ok=True than that would have been the obvious way to do it. -- Chris Green ·

1 0