🌐 Mailman 3 December 2016 - Python-list - python.org

Re: learning and experimenting python.
by einstein1410＠gmail.com Dec. 31, 2016

Dec. 31, 2016

Ethan, If you think I am wasting time, don't read my posts. Why wasting your time in reading my post. Are you having the answer of my question? Till now no one is able to give answer, everybody just assuming something and answering. No answer is perfect that satisfy why it uses >>>. Except lan's answer. Lan told that it is successor of ABC that's why it uses the >>> style. Now I got my answer. But next question is Why it for ABC? I know this is python group but it's reasonable doubt. If no doubts like this arises in your mind then you are just doing programming like Robot does and compiler converts the code in to machine language, it does not understand. Same you are doing man. Once again thanks a lot LAN for satisfiable answer.

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Re: Cleaning up conditionals
by Jussi Piitulainen Dec. 31, 2016

Dec. 31, 2016

"Deborah Swanson" <python(a)deborahswanson.net> writes: > Michael Torrie wrote: >> On 12/30/2016 05:26 PM, Deborah Swanson wrote: >> > I'm still wondering if these 4 lines can be collapsed to one or two >> > lines. >> >> If the logic is clearly expressed in the if blocks that you >> have, I don't see why collapsing an if block into one or two >> lines would even be desirable. Making a clever one-liner out >> of something isn't always a good thing. In fact some >> programmers don't like to use the ternary operator or >> conditional expressions, preferring to use explicit if block logic. >> > > Maybe it isn't always a good thing, but learning the capabilities of > python is. Besides, if the concern is future maintenance, a lot would > depend on the proficiency of those expected to maintain the code. One line: l1[st], l2[st] = (l1[st] or l2[st]), (l2[st] or l1[st]) (The parentheses are redundant.) Two lines: l1[st] = l1[st] or l2[st] l2[st] = l2[st] or l1[st] Both of these store the same value back in the given field if it's considered true (non-empty), else they store the corresponding value from the other record in the hope that it would be considered true (non-empty).

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Problem with running python 3.6.0 on a 32 bit windows 7 ultimate operating system.
by Sagar Utlas Dec. 31, 2016

Dec. 31, 2016

I am new to python, I've been using C++ as as a student till last 3 years. To expand my knowledge, I installed Python 3.6.0 and when tried to open it, a pop up window appeared saying- "The program can't start because api-ms-win-crt-runtime-|1-1-0.dll is missing from your computer. try reinstalling the program to fix this problem." I tried repairing the software using the setup, but again it was the same. What else can I do to run Python on my system.

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Re: learning and experimenting python.
by einstein1410＠gmail.com Dec. 31, 2016

Dec. 31, 2016

LAN you are right. I am agree with you that it's easy to recognise. But look $ for normal user # for special user/root % for other shell >>> For python And so on... Why? Why their developer selected that? Is there any special reason?

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List comprehension
by Jason Friedman Dec. 31, 2016

Dec. 31, 2016

$ python Python 3.6.0 (default, Dec 26 2016, 18:23:08) [GCC 4.8.4] on linux Type "help", "copyright", "credits" or "license" for more information. >>> data = ( ... (1,2), ... (3,4), ... ) >>> [a for a in data] [(1, 2), (3, 4)] Now, this puzzles me: >>> [x,y for a in data] File "<stdin>", line 1 [x,y for a in data] ^ SyntaxError: invalid syntax I expected: [(1, 2), (3, 4)]

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Re: List comprehension
by Steve D'Aprano Dec. 31, 2016

Dec. 31, 2016

On Sat, 31 Dec 2016 06:37 am, Jason Friedman wrote: > $ python > Python 3.6.0 (default, Dec 26 2016, 18:23:08) > [GCC 4.8.4] on linux > Type "help", "copyright", "credits" or "license" for more information. >>>> data = ( > ... (1,2), > ... (3,4), > ... ) >>>> [a for a in data] > [(1, 2), (3, 4)] > > Now, this puzzles me: > >>>> [x,y for a in data] > File "<stdin>", line 1 > [x,y for a in data] > ^ > SyntaxError: invalid syntax > > I expected: > [(1, 2), (3, 4)] Why would you expect that? I would expect the global variables x and y, or if they don't exist, a NameError: py> a = (1, 2) py> x, y Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'x' is not defined Python has no magic that "x and y mean the first two items of a". Instead, you get a syntax error because the syntax is ambiguous: [x,y for a in data] looks like a list [x, y] except the second item is a syntax error "y for a in data". So let's fix the syntax error: py> data = [(1, 2), (3, 4)] py> [a for a in data] [(1, 2), (3, 4)] py> [(x, y) for a in data] Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 1, in <listcomp> NameError: name 'x' is not defined Okay, let's create global variables x and y: py> x = 98 py> y = 99 py> [(x, y) for a in data] [(98, 99), (98, 99)] No surprises there. How about this instead: py> [(x, y) for (x, y) in data] [(1, 2), (3, 4)] That's better! -- Steve “Cheer up,” they said, “things could be worse.” So I cheered up, and sure enough, things got worse.

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Re: learning and experimenting python.
by einstein1410＠gmail.com Dec. 31, 2016

Dec. 31, 2016

But in his website, he recommended that post your questions here, he will answer it. But still as you told me I will send him an personal e-mail.

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RE: Cleaning up conditionals
by Deborah Swanson Dec. 31, 2016

Dec. 31, 2016

> On Fri, 30 Dec 2016 13:20:15 -0800, "Deborah Swanson" > <python(a)deborahswanson.net> declaimed the following: > > >I've already learned one neat trick to collapse a conditional: > > > > a = expression1 if condition else expression2 > > > >Here I have a real mess, in my opinion: > > > > if len(l1[st]) == 0: > > if len(l2[st]) > 0: > > l1[st] = l2[st] > > elif len(l2[st]) == 0: > > if len(l1[st]) > 0: > > You will never reach here. The above "elif" is only > reachable if "len(l1[st])" IS EQUAL TO 0, which means that > the later "if" can not be true. > > > l2[st] = l1[st] > > > > (Basically, if one field from two adjacent rows is empty and the > >other is > > not, copy the non-empty field to the empty one. I use this > for rental > > listings that are identical but posted on different dates, > to copy the > > > > data from an older one to the new one. Or, if I look up > the data for > >a new > > listing, to copy it back to the older ones.) > > > >Anybody know or see an easier (more pythonic) way to do > this? I need to > >do it for four fields, and needless to say, that's a really > long block > >of ugly code. > > > > Ever consider using conjunctions? > > if len(l1[st]) and not len(l2[st]): > #0 is considered a false -- no need to test for "==0" > #non-0 is considered true -- no need to test for ">0" > #copy l1 to l2 > elif not len(l1[st]) and len(l2[st]): > #copy l2 to l1 > > -- > Wulfraed Dennis Lee Bieber AF6VN > wlfraed(a)ix.netcom.com HTTP://wlfraed.home.netcom.com/ That's a neat shortcut, len(a) instead of len(a)!= 0. Thanks! Yes, 4 lines is an improvement on 6 lines, but I was hoping for something more radical. Is it possible to use some version of the "a = expression1 if condition else expression2" syntax with an elif? And for expression1 and expression2 to be single statements? That's the kind of shortcutting I'd like to do, and it seems like python might be able to do something like this.

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Re: learning and experimenting python.
by einstein1410＠gmail.com Dec. 31, 2016

Dec. 31, 2016

Thanks once again. Its only you who gave me the satisfied answer. Now it's my task to identify the reason why ABC used >>> ?

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Re: learning and experimenting python.
by Wildman Dec. 31, 2016

Dec. 31, 2016

On Fri, 30 Dec 2016 23:39:43 +0000, Erik wrote: > On 30/12/16 23:34, einstein1410(a)gmail.com wrote: >> You are also confusing me. >> But there mustbe some reason. >> What happens if your student questions you like this.? >> And may be those who questions like this will surely be the developer of its successor language. >> Because out of thousands, only one may asks this, whom you all will consider fool, but he's the only genius > > Do not feed the troll. > > E. Please explain how what I said is trolling. Perhaps it was a little snide but I tend to get that way when trying to explain the obvious. -- <Wildman> GNU/Linux user #557453 The cow died so I don't need your bull!

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