🌐 Mailman 3 December 2014 - Python-list - python.org

Re: CSV Dictionary
by JC Dec. 29, 2014

Dec. 29, 2014

On Mon, 29 Dec 2014 10:32:03 -0600, Skip Montanaro wrote: > On Mon, Dec 29, 2014 at 10:11 AM, JC <chalao.adda(a)gmail.com> wrote: >> Do I have to open the file again to get 'rdr' work again? > > Yes, but if you want the number of records, just operate on the rows > list, e.g. len(rows). > > Skip Yes, I did that. But if I need to use 'rdr' again, I have to open it again, right? Is there any ways to get 'rdr' point to first record again? Thanks.

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Re: suggestions for VIN parsing
by Rick Johnson Dec. 29, 2014

Dec. 29, 2014

On Sunday, December 28, 2014 5:34:11 PM UTC-6, Vincent Davis wrote: > > [snip: code sample with Unicode spaces! Yes, *UNICODE SPACES*!] Oh my! Might i offer some suggestions to improve the readability of this code? 1. Indexing is syntactically noisy, so if you find yourself fetching the same index more than once, then that is a good time to store the indexed value into a local variable. 2. The only thing worse than duplicating code which fetches the same index over and over again, is wrapping the fetch in casting function (in this case: "int()") OVER and OVER again! 3. I see that you are utilizing regexps to aid in the logic, and although i agree that regexps are overkill for this problem (since it could "technically" be solved with string methods) if *I* had to solve this problem, i would use the power of regexps -- although i would use them more wisely ;-) I have not studied the data thoroughly, but just by "grazing over" the code you posted i can see a few distinct patterns that emerge from the VIN data-set. Here is a description of the patterns: "\d+n" "\d+na" "d\d+" "du\d+" and the last pattern being all digits: "\d+" Even though your "verbose-run-on-conditional" would most likely execute faster, i prefer to write code (when performance is not mission critical!) in the most readable and maintainable fashion. And in order to achieve that goal, you always want to keep the main logic as succinct as possible whist encapsulating the difficult bits in "suitably abstracted structures". DIVIDE AND CONQUER! ============================================================ My approach would be as follows: ============================================================ 1. Create a map for each distinct set of VIN patterns with the keys being a two-tuple that represents the low and high limits of the serial number, and the values being the year of that range.. database = { 'map_NA':{ (101, 15808): "Triumph 1951", (15809, 25000): "Triumph 1952", ..., }, 'map_N':{ ..., }, 'map_H':{ ..., }, 'map_D':{ ..., }, 'map_DU':{ ..., }, } 2. Create a regexp pattern for each "distinct VIN pattern". The group captures will be used to strip-out *ONLY* the numeric parts! Then concatenate all the regexp patterns into a single monolithic program utilizing "named groups". (The group names will be the corresponding "map_*" for which to search) [code stub here] :-P" 3. Now you can write some fairly simple logic. prog = re.compile("pat1|pat2|pat3...") def parse_vin(vin): match = prog.search(vin) if match: gname = # Fetch the groupname from the match object. number = # Fetch the digits from the group capture. d = database[gname] for k in d: low, high = d[k] if low <= number <= high: return d[k] return None While this approach could be "heavy handed", i feel it will be much easier to maintain and expand. I'd argue that if you're going to utilize re's, then you should wield the full power they provide, else, use some other method. PS: You know you have a Unicode monkey on your back when you use tools that insert Unicode spaces! PPS: Hopefully i did not make any stupid mistakes, it's past my bedtime!

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Re: suggestions for VIN parsing
by Denis McMahon Dec. 29, 2014

Dec. 29, 2014

On Sun, 28 Dec 2014 16:27:20 -0700, Vincent Davis wrote: > On Fri, Dec 26, 2014 at 12:15 PM, Denis McMahon > <denismfmcmahon(a)gmail.com> > wrote: > >> Note, I think the 1981 model year ran KCA - DCA prefixes, not as shown >> on the website you quoted. > Denis, > Regarding the KCA - DCA prefixes, do you have a source as to why you > think this? Study the website carefully. Calculate the prefixes for the 1981 and 1982 model years according to the table on the website. K .. D would be the appropriate month prefixes for the 1981 model year, but if both the 1981 and 1982 model years used DA as a year prefix, there would be some prefixes that appeared twice, in the 1981 model year and the 1982 model year. Which suggests to me that there's been a slip up somewhere. -- Denis McMahon, denismfmcmahon(a)gmail.com

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Re: Future of python on android
by Anssi Saari Dec. 29, 2014

Dec. 29, 2014

"Fetchinson ." <fetchinson(a)googlemail.com> writes: > So what's the future proof way of writing/deploying/installing python > programs on android? Kivy is it I believe. I've meant to look into it but haven't gotten around to it...

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Re: CSV Dictionary
by JC Dec. 29, 2014

Dec. 29, 2014

On Mon, 29 Dec 2014 09:47:23 -0600, Skip Montanaro wrote: > On Mon, Dec 29, 2014 at 9:35 AM, JC <chalao.adda(a)gmail.com> wrote: >> How could I get the all the records? > > This should work: > > with open('x.csv','rb') as f: > rdr = csv.DictReader(f,delimiter=',') > rows = list(rdr) > > You will be left with a list of dictionaries, one dict per row, keyed by > the values in the first row: > >>>> import csv with open('x.csv','rb') as f: > ... rdr = csv.DictReader(f,delimiter=',') > ... rows = list(rdr) > ... >>>> import pprint pprint.pprint(rows) > [{'id': '1', 'name': 'ABC', 'password': '1234', 'userid': 'def@ghi'}, > {'id': '2', 'name': 'DEF', 'password': 'asdf', 'userid': 'ghi@jkl'}, > {'id': '3', 'name': 'GHI', 'password': 'zxcv', 'userid': 'jkl@mno'}] > > Skip Thanks. That did the job. But now I see another problem. I cannot use the "rdr" object anymore. For example, I wanted to count the number of records. I used - count = sum(1 for r in rdr) It returned 0 records. Do I have to open the file again to get 'rdr' work again? Thanks again.

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Python 2.7 segfaults on 'import site'
by Chris Angelico Dec. 29, 2014

Dec. 29, 2014

rosuav@sikorsky:~$ python -S Python 2.7.3 (default, Mar 13 2014, 11:03:55) [GCC 4.7.2] on linux2 >>> rosuav@sikorsky:~$ python Segmentation fault This is the system Python on Debian Wheezy, and I haven't changed site.py at all. This broke some time in the last few days, and I'm trying to figure out why. (I have been fiddling with my python3, but the system Python is untouched, as you can see from the above.) Attempting to 'import site' manually causes the same segfault; things get interesting if I create my own local site.py though: rosuav@sikorsky:~/aaa$ touch site.py rosuav@sikorsky:~/aaa$ python Segmentation fault rosuav@sikorsky:~/aaa$ python -S Python 2.7.3 (default, Mar 13 2014, 11:03:55) [GCC 4.7.2] on linux2 >>> import site >>> So clearly an empty 'site' can be imported safely, but running Python without -S segfaults. Can anyone advise as to where I should look for the cause of the trouble? ChrisA

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CSV Dictionary
by JC Dec. 29, 2014

Dec. 29, 2014

Hello, I have csv file like: id,name,userid,password 1,ABC,def@ghi,1234 2,DEF,ghi@jkl,asdf 3,GHI,jkl@mno,zxcv . . . I need to get that csv file into a dictionary. Here is my code: import csv with open('x.csv','rb') as f: rdr = csv.DictReader(f,delimiter=',') flds = rdr.fieldnames rows = 0 d = {} for row in rdr: rows += 1 i = 0 for i in range(len(flds)): d[flds[i]] = row[flds[i]] It shows only the last record, like: d = {'Password': 'zxcv', 'UserId': 'jkl@mno', 'id': '3', 'Name': 'GHI'} How could I get the all the records? Thanks.

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Searching through more than one file.
by Seymore4Head Dec. 29, 2014

Dec. 29, 2014

I need to search through a directory of text files for a string. Here is a short program I made in the past to search through a single text file for a line of text. How can I modify the code to search through a directory of files that have different filenames, but the same extension? fname = raw_input("Enter file name: ") #"*.txt" fh = open(fname) lst = list() biglst=[] for line in fh: line=line.rstrip() line=line.split() biglst+=line final=[] for out in biglst: if out not in final: final.append(out) final.sort() print (final)

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Re: Own network protocol
by pfranken85＠gmail.com Dec. 29, 2014

Dec. 29, 2014

Hello Tim, Am Samstag, 27. Dezember 2014 14:19:21 UTC+1 schrieb Tim Chase: > The eventual solution would depend on a variety of factors: > > - how critical is synchronization? > > - do clients need to know if they missed a message? (somebody > disconnected from the LAN for a moment) This would be nice indeed. At least, the user should be notified that the connection was lost and the current values may not be uptodate any more. > - do clients need a way to receive historical messages in the event > they were offline during the broadcast? (a power outage knocked out > Client #18 at the time of the last update) no, this is not necessary. > > - are all your clients on the same IP subnet? (you could use a > broadcast packet) yes, this assumption can be made. > > - would you rather push data as it changes, or have clients poll for > the current state? (you write "it should send the update to the > connected clients" which suggests a push architecture, yet you also > want to have clients able to send updates: "should be possible for > the client to send a particular request to the server...i.e., switch > on LEX X") Indeed, I would prefer a "push" setting, in particular to avoid additional overhead from the constant polling. Besides, this resembles more the scenario present at the server side: it gets notifications via callbacks in case anything has changed. > - are you concerned about security/authentication? Can a rogue device > send a message pretending to be the server? What would/should > happen if an unintended client snoops the traffic? Does it matter? > The suggestions would look very different if you were just building a > hobby notification system as a demo in a contained home/lab/office, > vs. if you were building an industrial control system for monitoring a > remote location and conveying security info. Concerning the latter two points: Introducing a possible security layer is something I would like to do in the future, so the selection of the network protocol/system should definitely keep this in mind. What do you think of the RPyC? Thanks for your valuable input!

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Re: Searching through more than one file.
by Albert-Jan Roskam Dec. 29, 2014

Dec. 29, 2014

----------------------------- On Sun, Dec 28, 2014 8:12 PM CET Dave Angel wrote: >On 12/28/2014 12:27 PM, Seymore4Head wrote: >> I need to search through a directory of text files for a string. >> Here is a short program I made in the past to search through a single >> text file for a line of text. >> >> How can I modify the code to search through a directory of files that >> have different filenames, but the same extension? >> > >You have two other replies to your specific question, glob and os.listdir. I would also mention the module fileinput: > >https://docs.python.org/2/library/fileinput.html Ah, I was just about to say that. I found out about this gem after reading Dough Helmann's book. Here are some usage examples: http://pymotw.com/2/fileinput/ >import fileinput >from glob import glob > >fnames = glob('*.txt') >for line in fileinput.input(fnames): > pass # do whatever > >If you're not on Windows, I'd mention that the shell will expand the wildcards for you, so you could get the filenames from argv even simpler. See first example on the above web page. > > >I'm more concerned that you think the following code you supplied does a search for a string. It does something entirely different, involving making a crude dictionary. But it could be reduced to just a few lines, and probably take much less memory, if this is really the code you're working on. > >> fname = raw_input("Enter file name: ") #"*.txt" >> fh = open(fname) >> lst = list() >> biglst=[] >> for line in fh: >> line=line.rstrip() >> line=line.split() >> biglst+=line >> final=[] >> for out in biglst: >> if out not in final: >> final.append(out) >> final.sort() >> print (final) >> > >Something like the following: > >import fileinput >from glob import glob > >res = set() >fnames = glob('*.txt') >for line in fileinput.input(fnames): > res.update(line.rstrip().split()) >print sorted(res) > > > > >-- DaveA >-- https://mail.python.org/mailman/listinfo/python-list

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