🌐 Mailman 3 November 2018 - Python-list - python.org

What Python books to you recommend to beginners?
by Skip Montanaro Nov. 28, 2018

Nov. 28, 2018

I've been using Python since long before Mark Lutz's book was first released, so I've never paid much attention to what's out there. Still, every now and then, someone asks me for a recommendation (as just happened a few minutes ago). "Learning Python" was last released in 2013 (Python 3.3), so lacks many newer features of the language. What do people recommend? The target is Python 3.6 and 3.7. The audience at work is a mostly financial/statistical crowd, so exposure to things like Pandas would be nice, though I'm sure there are dedicated books for just that. Thanks, Skip

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PEP 572 -- Assignment Expressions
by Ivo Shipkaliev Nov. 28, 2018

Nov. 28, 2018

Hello. Maybe it's too late for a discussion, but I just couldn't resist. I just found out about this new ":=" operator. I need to ask: What is the need for this additional ":" to the "="? Why: if (match := pattern.search(data)) is not None: # Do something with match What is wrong with: if match = pattern.search(data) is not None: # Do something with match Assignment expression or assignment statement, it's an assignment, right? It is very clear to everyone that it's an assignment! Can't it all just be a "="? Thank you very much! Kind Regards Ivo Shipkaliev

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Question on difference between LambdaType and FunctionType
by Iwo Herka Nov. 27, 2018

Nov. 27, 2018

Hello, Can someone please provide a use-case for having LambdaType separate to FunctionType? Since they are equal (LambdaType == FunctionType) it seems a bit superfluous to me. For example, I cannot do the following: if type(foo) is FunctionType and not type(foo) is LambdaType: ... What am I missing? Sincerely, Iwo Herka

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how to match list members in py3.x
by Muhammad Rizwan Nov. 26, 2018

Nov. 26, 2018

for each word in each line how can we check to see if a word is already present in a list and if it is not how to append that word to a new list

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Improvement Request
by Sayan Kundu Nov. 26, 2018

Nov. 26, 2018

*** Please make "Table of Contents" an independent scrolling panel* For a long documentation, users have to scroll up all the way to navigate a different sub-topic.

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Re: help me in a program in python to implement Railway Reservation System using file handling technique.
by Mario R. Osorio Nov. 26, 2018

Nov. 26, 2018

On Saturday, November 24, 2018 at 1:44:21 AM UTC-5, Chris Angelico wrote: > On Sat, Nov 24, 2018 at 5:36 PM <jasminamrutia007(a)gmail.com> wrote: > > > > hello all, > > please hepl me in the above program. python to implement Railway Reservation System using file handling technique. > > > > System should perform below operations. > > a. Reserve a ticket for a passenger. > > b. List information all reservations done for today’s trains. > > We won't do your homework for you. Have a shot at writing it yourself > first, and then if you need help, bring specific questions to the > list. > > ChrisA Specially not for an Assistant Professor at SMT.R.O.PATEL WOMEN'S MCA COLLEGE holding an MBA and a BCA... Shame on you Jasmin!

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Re: Python2.7 unicode conundrum
by Robert Latest Nov. 26, 2018

Nov. 26, 2018

Richard Damon wrote: > Why do you say it has been convert to 'Latin'. The string prints as > being Unicode. Internally Python doesn't store strings as UTF-8, but as > plain Unicode (UCS-2 or UCS-4 as needed), and code-point E4 is the > character you want. You're right, this wasn't the minimal example for my problem after all. Turns out that the actual issue is somewhere between SQLAlchemy and MySQL. I took a more specific questioon overt to stackoverflow.com Thanks robert

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Re: how to match list members in py3.x
by Michael F. Stemper Nov. 25, 2018

Nov. 25, 2018

On 25/11/2018 11.41, Richard Damon wrote: > On 11/25/18 12:28 PM, Muhammad Rizwan wrote: >> handle = open('file.txt') >> newlist = list() >> for line in handle: >> #line.rstrip() >> linewords = line.split() >> print(linewords) >> >> for word in linewords: >> newlist.append(word) >> if word not in linewords: >> continue >> >> >> >> print('new: ',newlist) > > The first thing I note in looking at this is that the second loop will > run AFTER the first loop completes, not for each step of the loop, > because you outdented the code. > > Also, you unconditionally add the word, and THEN check if it is in the list. And the first thing that I note is that he checks to see if it is in the list from which it came. -- Michael F. Stemper Economists have correctly predicted seven of the last three recessions.

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Issue in using "subprocess.Popen" for parsing the command output
by srinivasan Nov. 25, 2018

Nov. 25, 2018

Dear Python Experts Team, As am newbie still learning the python syntax from past 2 weeks, Excuse me, If this might be silly question, As I am trying to execute shell command (ie, nmcli) using "subprocess.Popen". 1. Am trying to improve the below code with "try" and "exception", could you please help me how "try" and "exception" can be used on the below code snippet. I hope in my code with try and exception, seems to be a bug. 2. As I am trying to execute shell commands using "subprocess.Popen", I am trying to parse the strings output by "cmd = "nmcli device wifi connect '%s' password '%s'" % (ssid, pw)" command as below, but it is throwing the below error as shown in "Output error logs:" Could you please let me to fix the bug in the below code snippet, where I need the collect the strings of the command output and later how to be parsed after execution of the command for example, I need to parse the string "Connection activation failed: " and compare it with the command output, could you please help me how this can be achieved? *Command:* :~$ nmcli device wifi connect 'Apartment 18' password '40672958689850014685abcdf' Error: Connection activation failed: (7) Secrets were required, but not provided. :~$ *Code:* *import sys* *import subprocess* *interface = "wlan0"* *def main(ssid, pw):* * # cmd = "nmcli device wifi connect '%s' password '%s'" % (ssid, pw)* * #* * # proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True, universal_newlines=True)* * # stdout, stderr = proc.communicate()* * # retcode = proc.returncode* * #* * # print("printing stdout!!!!!!!!!!", stdout)* * # print("printing retcode!!!!!!!!!!", retcode)* * try:* * cmd = "nmcli device wifi connect '%s' password '%s'" % (ssid, pw)* * proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True, universal_newlines=True)* * stdout, stderr = proc.communicate()* * retcode = proc.returncode* * print("printing stdout!!!!!!!!!!", stdout)* * print("printing retcode!!!!!!!!!!", retcode)* * except subprocess.CalledProcessError as e:* * s = """While executing '{}' something went wrong.* * Return code == '{}'* * Return output:\n'{}'* * """.format(cmd, e.returncode, e.output, shell=enable_shell)* * raise AssertionError(s)* * return proc.strip().decode("utf-8")* *main("Apartment 18", "40672958689850014685")* *Output error logs:* /home/srinivasan/Downloads/wifidisconnectissuenov23/qa/venv/bin/python /home/srinivasan/Downloads/wifidisconnectissuenov23/qa/test_library/test4.py Traceback (most recent call last): File "/home/srinivasan/Downloads/wifidisconnectissuenov23/qa/test_library/test4.py", line 38, in <module> printing stdout!!!!!!!!!! printing retcode!!!!!!!!!! 0 main("Apartment 18", "40672958689850014685") File "/home/srinivasan/Downloads/wifidisconnectissuenov23/qa/test_library/test4.py", line 36, in main return proc.strip().decode("utf-8") AttributeError: 'Popen' object has no attribute 'strip' Process finished with exit code 1 Kindly do the needful as am stuck with this issue from 2 days Many Thanks in advance,

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Python2.7 unicode conundrum
by Robert Latest Nov. 25, 2018

Nov. 25, 2018

Hi folks, what semmingly started out as a weird database character encoding mix-up could be boiled down to a few lines of pure Python. The source-code below is real utf8 (as evidenced by the UTF code point 'c3 a4' in the third line of the hexdump). When just printed, the string "s" is displayed correctly as 'ä' (a umlaut), but the string representation shows that it seems to have been converted to latin-1 'e4' somewhere on the way. How can this be avoided? dh@jenna:~/python$ cat unicode.py # -*- encoding: utf8 -*- s = u'ä' print(s) print((s, )) dh@jenna:~/python$ hd unicode.py 00000000 23 20 2d 2a 2d 20 65 6e 63 6f 64 69 6e 67 3a 20 |# -*- encoding: | 00000010 75 74 66 38 20 2d 2a 2d 0a 0a 73 20 3d 20 75 27 |utf8 -*-..s = u'| 00000020 c3 a4 27 0a 0a 70 72 69 6e 74 28 73 29 0a 70 72 |..'..print(s).pr| 00000030 69 6e 74 28 28 73 2c 20 29 29 0a 0a |int((s,))..| 0000003c dh@jenna:~/python$ python unicode.py ä (u'\xe4',) dh@jenna:~/python$

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