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

Re: Everything good about Python except GUI IDE?
by Marko Rauhamaa June 6, 2016

June 6, 2016

Chris Angelico <rosuav(a)gmail.com>: > On Wed, Mar 2, 2016 at 4:41 PM, Marko Rauhamaa <marko(a)pacujo.net> wrote: >> I was talking about JSON for the standard I/O, not the command-line >> arguments, as in: >> >> ps -ef | awk '/httpd/ { print $2 }' >> >> where "ps -ef" emits SPC-separated fields and LF-separated records, and >> awk parses and processes them. > > If you want to change that, you have to change the entire ecosystem, > not just the shell. You would have to teach every single program to > use a different structure. Correct. There could be translation utilities in the interim. > A lot of programs already do support NUL-separation - usually with a > -z parameter or something. But you won't be able to magically get them > all to use JSON. And I doubt it would be advantageous anyway. The advantages are obvious. Barely any programs do proper escaping, and security problems abound. Maybe a starting point would be a Python Toybox (<URL: https://en.wikipedia.org/wiki/Toybox>). Ecosystem intertia aside, key to the success of such an endeavor would be to find a Python equivalent for ps -ef | awk '/httpd/ { print $2 }' that would be at least as convenient for the fingers and the eye. Marko

3 4

Basic Concepts
by Smith May 19, 2016

May 19, 2016

Fill in the blanks to declare a variable, add 5 to it and print its value: >>> x = 4 >>> x_ = 5 >>> print_ Any suggestion ? Thanks

5 4

Comparing Python enums to Java, was: How much sanity checking is required for function inputs?
by Ian Kelly May 5, 2016

May 5, 2016

On Sun, Apr 24, 2016 at 1:20 AM, Ethan Furman <ethan(a)stoneleaf.us> wrote: > On 04/23/2016 06:29 PM, Ian Kelly wrote: > >> Python enums are great. Sadly, they're still not quite as awesome as Java >> enums. > > > What fun things can Java enums do? Everything that Python enums can do, plus: * You can override methods of individual values, not just the class as a whole. Good for implementing the strategy pattern, or for defining a default method implementation that one or two values do differently. In Python you can emulate the same thing by adding the method directly to the instance dict of the enum value, so this isn't really all that much of a difference. * Java doesn't have the hokey notion of enum instances being distinct from their "value". The individual enum members *are* the values. Whereas in Python an enum member is an awkward class instance that contains a value of some other type. Python tries to get away from the C-like notion that enums are ints by making the enum members non-comparable, but then gives us IntEnum as a way to work around it if we really want to. Since Java enums don't depend on any other type for their values, there's nothing inviting the user to treat enums as ints in the first place. * As a consequence of the above, Java doesn't conflate enum values with their parameters. The Python enum docs give us this interesting example of an enum that takes arguments from its declaration: >>> class Planet(Enum): ... MERCURY = (3.303e+23, 2.4397e6) ... VENUS = (4.869e+24, 6.0518e6) ... EARTH = (5.976e+24, 6.37814e6) ... MARS = (6.421e+23, 3.3972e6) ... JUPITER = (1.9e+27, 7.1492e7) ... SATURN = (5.688e+26, 6.0268e7) ... URANUS = (8.686e+25, 2.5559e7) ... NEPTUNE = (1.024e+26, 2.4746e7) ... def __init__(self, mass, radius): ... self.mass = mass # in kilograms ... self.radius = radius # in meters ... @property ... def surface_gravity(self): ... # universal gravitational constant (m3 kg-1 s-2) ... G = 6.67300E-11 ... return G * self.mass / (self.radius * self.radius) ... >>> Planet.EARTH.value (5.976e+24, 6378140.0) >>> Planet.EARTH.surface_gravity 9.802652743337129 This is incredibly useful, but it has a flaw: the value of each member of the enum is just the tuple of its arguments. Suppose we added a value for COUNTER_EARTH describing a hypothetical planet with the same mass and radius existing on the other side of the sun. [1] Then: >>> Planet.EARTH is Planet.COUNTER_EARTH True Because they have the same "value", instead of creating a separate member, COUNTER_EARTH gets defined as an alias for EARTH. To work around this, one would have to add a third argument to the above to pass in an additional value for the sole purpose of distinguishing (or else adapt the AutoNumber recipe to work with this example). This example is a bit contrived since it's generally not likely to come up with floats, but it can easily arise (and in my experience frequently does) when the arguments are of more discrete types. It's notable that the Java enum docs feature this very same example but without this weakness. [2] * Speaking of AutoNumber, since Java enums don't have the instance/value distinction, they effectively do this implicitly, only without generating a bunch of ints that are entirely irrelevant to your enum type. With Python enums you have to follow a somewhat arcane recipe to avoid specifying values, which just generates some values and then hides them away. And it also breaks the Enum alias feature: >>> class Color(AutoNumber): ... red = default = () # not an alias! ... blue = () ... >>> Color.red is Color.default False Anyroad, I think that covers all my beefs with the way enums are implemented in Python. Despite the above, they're a great feature, and I use them and appreciate that we have them. [1] https://en.wikipedia.org/wiki/Counter-Earth [2] https://docs.oracle.com/javase/tutorial/java/javaOO/enum.html

3 9

crash while using PyCharm / Python3
by Adam May 3, 2016

May 3, 2016

Host OS: Ubuntu Desktop 14.04 LTS / Unity System crashed while using PyCharm / Python3. Booting takes forever and stuck at the purple screen with the Ubuntu logo and the five dots cycling. How to fix?

5 22

installing scipy
by Heli May 3, 2016

May 3, 2016

Hi all, I have a python34 installed on a windows-64bit machine. I am using Eclipse pydev editor. I need to used griddata from scipy.interpolate. I have installed scipy using by downloading the followng wheel file: scipy-0.17.0-cp34-none-win_amd64 and isntalling using pip install. The install is successful, but It seems like scipy is not installed correctly and I get the following error when trying to import and use scipy modules: C:\Python34\Scripts>python -c "import scipy.interpolate" Traceback (most recent call last): File "<string>", line 1, in <module> File "C:\Python34\lib\site-packages\scipy\interpolate\__init__.py", line 158, in <module> from .interpolate import * File "C:\Python34\lib\site-packages\scipy\interpolate\interpolate.py", line 11, in <module> import scipy.linalg File "C:\Python34\lib\site-packages\scipy\linalg\__init__.py", line 174, in <module> from .misc import * File "C:\Python34\lib\site-packages\scipy\linalg\misc.py", line 5, in <module> from .blas import get_blas_funcs File "C:\Python34\lib\site-packages\scipy\linalg\blas.py", line 155, in <module> from scipy.linalg import _fblas ImportError: DLL load failed How can I fix this problem? Thanks,

3 2

Re: Python Madlibs.py code and error message
by Steven D'Aprano May 3, 2016

May 3, 2016

On Thursday 28 April 2016 17:08, Stephen Hansen wrote: > On Wed, Apr 27, 2016, at 11:55 PM, Ben Finney wrote: >> Stephen Hansen <me(a)ixokai.io> writes: >> >> > On Wed, Apr 27, 2016, at 10:32 PM, Ben Finney wrote: >> > > Better: when you have many semantically-different values, use named >> > > (not positional) parameters in the format string. […] >> > > >> > > <URL:https://docs.python.org/3/library/string.html#formatstrings> >> > >> > Except the poster is not using Python 3, so all of this is for naught. >> >> Everything I described above works fine in Python 2. Any still-supported >> version has ‘str.format’. > > This response is completely unhelpful. The OP is using Python 2, and > using %-formatting, and so you give a series of examples of using > str.format, to, what? Confuse matters? How about we assume good faith and give Ben the benefit of the doubt that he simply made a minor and trivial misjudgement rather than accusing him of intentionally trying to confuse matters? You are correct that the OP can use % formatting with named arguments. Ben is correct that the OP can also change his code to use str.format. Some people hate %-formatting and cannot wait to migrate to {}-formatting, and some people don't. (For the record, Internet rumours that %-formatting is deprecated are simply not correct.) -- Steve

2 1

do_POST not working on http.server with python
by Rahul Raghunath May 1, 2016

May 1, 2016

0 down vote favorite I'm trying to create a simple http server with basic GET and POST functionality. The program is supposed to GET requests by printing out a simple webpage that greets a user and askes how he would rather be greeted. When the user enters a greeting of his choice, the webpage should now greet him as he had chosen. While GET seems to be working fine, POST is not. I tried debugging by printing at every code execution and it seems to be getting stuck here: ctype, pdict = cgi.parse_header(self.headers.getheader('content-type')) I'll paste the code full code below, along with my terminal output. Code: from http.server import BaseHTTPRequestHandler, HTTPServer import cgi class webServerHandler(BaseHTTPRequestHandler): def do_GET(self): try: if self.path.endswith("/hello"): self.send_response(200) self.send_header('Content-type', 'text/html') self.end_headers() output = "" output += "<html><body>" output += "<h1>Hello!</h1>" output += '''<form method='POST' enctype='multipart/form-data' action='/hello'><h2>What would you like me to say?</h2><input name="message" type="text" ><input type="submit" value="Submit"> </form>''' output += "</body></html>" self.wfile.write(output.encode(encoding = 'utf_8')) print (output) return if self.path.endswith("/hola"): self.send_response(200) self.send_header('Content-type', 'text/html') self.end_headers() output = "" output += "<html><body>" output += "<h1>&#161 Hola !</h1>" output += '''<form method='POST' enctype='multipart/form-data' action='/hello'><h2>What would you like me to say?</h2><input name="message" type="text" ><input type="submit" value="Submit"> </form>''' output += "</body></html>" self.wfile.write(output.encode(encoding = 'utf_8')) print (output) return except IOError: self.send_error(404, 'File Not Found: %s' % self.path) def do_POST(self): try: self.send_response(201) print("Sent response") self.send_header('Content-type', 'text/html') print("Sent headers") self.end_headers() print("Ended header") ctype, pdict = cgi.parse_header(self.headers.getheader('content-type')) print("Parsed headers") if ctype == 'multipart/form-data': fields = cgi.parse_multipart(self.rfile, pdict) messagecontent = fields.get('message') print("Receiver message content") output = "" output += "<html><body>" output += " <h2> Okay, how about this: </h2>" output += "<h1> %s </h1>" % messagecontent[0] output += '''<form method='POST' enctype='multipart/form-data' action='/hello'><h2>What would you like me to say?</h2><input name="message" type="text" ><input type="submit" value="Submit"> </form>''' output += "</body></html>" print(output) self.wfile.write(output.encode(encoding = 'utf_8')) print ("Wrote through CGI") except: pass def main(): try: port = 8080 server = HTTPServer(('', port), webServerHandler) print ("Web Server running on port", port) server.serve_forever() except KeyboardInterrupt: print (" ^C entered, stopping web server....") server.socket.close() if __name__ == '__main__': main() Terminal Output: Web Server running on port 8080 127.0.0.1 - - [28/Apr/2016 13:28:59] "GET /hello HTTP/1.1" 200 - <html><body><h1>Hello!</h1><form method='POST' enctype='multipart/form-data' action='/hello'><h2>What would you like me to say?</h2><input name="message" type="text" ><input type="submit" value="Submit"> </form></body></html> 127.0.0.1 - - [28/Apr/2016 13:29:09] "POST /hello HTTP/1.1" 201 - Sent response Sent headers Ended header As you can see, the POST function does not seem to go beyong the parse_header command. I cannot figure this out, and any help would be usefu!

2 1

Re: What should Python apps do when asked to show help?
by Steven D'Aprano May 1, 2016

May 1, 2016

On Sat, 30 Apr 2016 12:49 pm, Ben Finney wrote: > Random832 <random832(a)fastmail.com> writes: > >> On Fri, Apr 29, 2016, at 22:27, Rustom Mody wrote: >> > Instead it does some ½-assed fall-between-the-stools of both >> >> That doesn't answer the question of why, if you (Well, Ethan, but >> you're taking the same position here) hate pagers so much > > That's not a question relevant here; nobody inthe discussion has a > position fairly characterised as “hate pagers so much”. So you're > arguing against a straw man. > > Rather, the position being argued is that they *do* like pagers; they > like pagers enough that they want the existing ‘PAGER’ environment > variable setting to remain untouched. So they want the PAGER environment variable to specify what pager they want... > And, simulatenously, they want > Python's help to not use a pager at the interactive prompt. ...so long as applications don't actually make use of that PAGER environment variable to determine the pager they want to use. (1) If you want man, and nothing else in the universe, to automatically use a pager, then set MANPAGER="less" (or whatever you wish to use), and unset PAGER. (2) If you don't want *anything* to use a pager, then unset both MANPAGER and PAGER. You may have to report a feature request / bug report for applications which force their own pager. (3) In Python specifically, you can trivially and easily tell help() to output directly to stdout. (At least on Linux, I haven't tested it elsewhere.) Simply use PAGER=cat on the command line you use to launch the interactive environment. This will affect no other running or future processes (apart from subprocesses launched from your interactive Python session), allowing you to keep your PAGER for everything else. (4) If you want more than that, then patches are welcome :-) Seriously, I'm thinking that a keyword argument to help might be useful: help(object, pager=None) where: - pager=None gives the current behaviour; - pager="foo" calls out to the external program "foo"; - pager=callable passes the help text to callable(). pager=print would do exactly what people are asking for, and you could then create your own wrapper to change the default: help = functools.partial(builtins.help, pager=print) I think that would make it easier to test help(). Thoughts? -- Steven

6 11

Re: What should Python apps do when asked to show help?
by Steven D'Aprano May 1, 2016

May 1, 2016

On Fri, 29 Apr 2016 07:08 am, Grant Edwards wrote: > On 2016-04-28, Random832 <random832(a)fastmail.com> wrote: >> On Thu, Apr 28, 2016, at 15:39, Grant Edwards wrote: >>> That's fine. If you want two or three forms of documentation then you >>> prepare two or three forms of documentation. >>> >>> Adding an option to run the default 'help' output through a pager or >>> display it in a web browser doesn't somehow force you "to compose two >>> forms of documentation" unless you want two forms of documentation. >> >> The point is that having "help" output at all (beyond either a cursory >> "see the manpage") implies two forms of documentation (given you already >> have a manpage), and some people choose not to do that, instead >> launching directly into the manpage (which implies using a pager) > > But I'm saying that having --help output the manpage should not imply > using a pager. What manpage? I don't have a manpage. The only help my application has is whatever it outputs (which it gets from its docstring). What is a good place where I can find out more about writing manpages? > If --help is going to output the manpage, then I'm saying it can (and > should) be written to stdout without use of pager (and it shouldn't > have escape sequences or backspaces in it either). The Unix way is > that the output from whatever --help should be plain text written to > stdout (regardless of length). Agree. The -h/--help option will output plain text to stdout. > If you want to output the man page, this can be accomplished simply by > doing someting like: > > os.environ["GROFF_NO_SGR"] = "1"; > os.system("man -Tascii mycmd | col -bx"); That doesn't work for me: [steve@ando ~]$ man -Tasciii rm man: invalid option -- T However, this almost works: man -Pcat rm appears to output unformatted, plain text to stdout. However, if you capture the output (say, to a file) you'll see it is full of backspaces, e.g.: N^HNA^HAM^HME^HE rm - remove files or directories S^HSY^HYN^HNO^HOP^HPS^HSI^HIS^HS r^Hrm^Hm [_^HO_^HP_^HT_^HI_^HO_^HN]... _^HF_^HI_^HL_^HE... instead of NAME rm - remove files or directories SYNOPSIS rm [OPTION]... FILE... Apparently `less` understands overstriking and displays it as bold (or underlining in the case of _^H. That's very clever, but how do I get actual plain text out of `man` without the backspaces? > If I want the --help output run through a pager, I'll do it myself. Easy enough to say for Linux/Unix users, but there are those who might not have a pager that is easy to use, or at all. pydoc goes to considerable trouble to work out the best pager available for your platform, falling back to its own if needed. To use that is literally a two liner: import pydoc pydoc.pager(HELPTEXT) -- Steven

5 5

How to fill in abbreviation in one column based on state name in another column?
by David Shi April 30, 2016

April 30, 2016

I am trying to use apply to execute a lookup function, so that we can put abbreviation in a new column, in accordance to a state name in another column. Does anyone knows how to make this to work? Regards. David state_to_code = {"VERMONT": "VT", "GEORGIA": "GA", "IOWA": "IA", "Armed Forces Pacific": "AP", "GUAM": "GU", "KANSAS": "KS", "FLORIDA": "FL", "AMERICAN SAMOA": "AS", "NORTH CAROLINA": "NC", "HAWAII": "HI", "NEW YORK": "NY", "CALIFORNIA": "CA", "ALABAMA": "AL", "IDAHO": "ID", "FEDERATED STATES OF MICRONESIA": "FM", "Armed Forces Americas": "AA", "DELAWARE": "DE", "ALASKA": "AK", "ILLINOIS": "IL", "Armed Forces Africa": "AE", "SOUTH DAKOTA": "SD", "CONNECTICUT": "CT", "MONTANA": "MT", "MASSACHUSETTS": "MA", "PUERTO RICO": "PR", "Armed Forces Canada": "AE", "NEW HAMPSHIRE": "NH", "MARYLAND": "MD", "NEW MEXICO": "NM", "MISSISSIPPI": "MS", "TENNESSEE": "TN", "PALAU": "PW", "COLORADO": "CO", "Armed Forces Middle East": "AE", "NEW JERSEY": "NJ", "UTAH": "UT", "MICHIGAN": "MI", "WEST VIRGINIA": "WV", "WASHINGTON": "WA", "MINNESOTA": "MN", "OREGON": "OR", "VIRGINIA": "VA", "VIRGIN ISLANDS": "VI", "MARSHALL ISLANDS": "MH", "WYOMING": "WY", "OHIO": "OH", "SOUTH CAROLINA": "SC", "INDIANA": "IN", "NEVADA": "NV", "LOUISIANA": "LA", "NORTHERN MARIANA ISLANDS": "MP", "NEBRASKA": "NE", "ARIZONA": "AZ", "WISCONSIN": "WI", "NORTH DAKOTA": "ND", "Armed Forces Europe": "AE", "PENNSYLVANIA": "PA", "OKLAHOMA": "OK", "KENTUCKY": "KY", "RHODE ISLAND": "RI", "DISTRICT OF COLUMBIA": "DC", "ARKANSAS": "AR", "MISSOURI": "MO", "TEXAS": "TX", "MAINE": "ME"} #table['moa_state_name'] = map(lambda x: x.upper(), table['moa_state_name'])def convert_state(row): abbrev1 = state_to_code(table['moa_state_name']) #'aatest' if abbrev1: return abbrev1 ##state_to_code[abbrev[0]] return np.nan#print convert_state(table['moa_state_name']) table.insert(0, "abbrev", np.nan)table['abbrev'] = table.apply(convert_state, axis=1) print state_to_code['ARKANSAS']

3 2