🌐 Mailman 3 December 2007 - Tutor - python.org

Send binary/hex data to a TCP socket
by Tod Haren July 19, 2011

July 19, 2011

I need to send a server at the other end of a socket a 36 byte "frame", where each byte represents a specific field in the custom data structure. (If there are any Ham operators reading this, I'm talking about the AGW Packet Engine) The documentation for the server says to initialize each field to a binary zero(0x00). How do I get a binary zero in Python? The next step is to send this all to the server and subsequently receive a similarly formated frame. A very basic frame looks something like this(modified from documentation): |00 00 00 00 4D 00 00 00 00 00 00 00 00 00 00 00 |....M........... |00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................ |00 00 00 00 |.... My problem is that hex(0) return '0x0' and hex(ord('M')) returns '0x4d'. If I concatonate these all together then the socket receives 109 bytes instead of 36. The documentation examples are in C++, so they are little help to me. The examples make use of the MoveMemory function for building the frames, but I'm clueless what that does. Pseudo code for the frame above: l = [] for i in xrange(36): l.append(hex(0)) l[4]=hex(ord('M')) d='' d=d.join(l) #I need some other data type to send besides a string! sock.send(d) #send the 36 bytes to the socket Any pointers or references would be greatly appreciated.

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Tracking time
by Michael Key Jan. 6, 2010

Jan. 6, 2010

I am trying to develop a project tracking program that would allow you to track hours and minutes spent on several different projects and store he data in a database for printing. Any help would be appreciated. Mike

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Learning Python
by Fred P Dec. 13, 2009

Dec. 13, 2009

Hey Everyone, I am completely new at python, but not new to programming or scripting. I have a couple of years of LUA scripting experience, about a year of C++ classes, and used to be very efficient at c-shell scripting in unix. My question for you guys: 1) How do I get Started? 2) Recommend any specific Books? 3) Any online tutors/ forums that would benefit a newbie 4) Any online classes that teach python? I have taken online c++ courses, and found them helpful. I was hoping to find something for python. My main objective is to write scripts for the following type of applications File management, file copies/syncs/ compares Text manipulation - like parsing text files to replace or augment specific values Integration into current applications to write redundant routines and maybe some day plugins I am not even sure what else, but I do know that every time i think of something that we need at work, other people say, "That would be a good task for a python script" and I would eventually like to be able to do something about that. Thanks Fred

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Re: [Tutor] Parsing DICOMRT file
by John Fouhy March 15, 2008

March 15, 2008

On 13/12/2007, Bryan Fodness <bryan.fodness(a)gmail.com> wrote: > I am new to doing anything like this. I have looked at > http://www.leadtools.com/SDK/Medical/DICOM/ltdc1.htm and am > not sure how to proceed. I haven't much experience here, but this is how I'd proceed, I think: 1. Start by reading the file. It's binary data (I guess) so there's no point in reading lines.: rawData = open('file.dcm', 'rb').read() 2. Write a function to parse the preamble: def parsePreamble(data): preamble = data[:128] dicm = data[128:132] # you might need to read up on encodings and things to make sure this test is valid if dicm == 'DICM': return preamble, 132 else: raise NotAPreambleException 3. Write functions to parse data elements. The functions are going to try to parse a data element starting at a particular position, and if successful, return the position of the end of the element. def parseDataelement(data, start): # do stuff -- the web page you linked didn't have enough information here return element, pos 4. Parse the whole thing; def parseDICOM(data): elements = [] try: preamble, next = parsePreamble(data) except NotAPreambleException: preamble, next = None, 0 while True: element, next = parseDataElement(data, next) elements.append(element) # you will need some way of breaking out of this loop, either by checking the structure of # element for an end condition, or by parseDataElement raising an exception. return elements # and maybe preamble too if you want it HTH!

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user-given variable names for objects
by Che M Feb. 28, 2008

Feb. 28, 2008

I'm sure this is a classic beginner's topic, and I've read a bit about it online already, but I'd like to ask about it here as well. I want to assign names to objects based on what a user inputs so that I can later keep track of them. In particular, I want to time multiple events by getting each of their start times and later comparing them to their respective stop times--I don't want to user timers. In order to do this, I need to give each start time a name associated with the name of the event. If there is an "event A" it's start time could be eventA_start, whereas event B could be called eventB_start, i.e.: eventA_start = datetime.datetime.now() The problem is, I don't know the "A" part...the user could choose eventPotato or eventDinosaur. I won't know in advance. I want the name chosen/inputted by the user to be attached to the name for the time that event started. I have read that the way to do this properly in Python is with use of dictionaries, but I haven't found a reference online that shows how to do it is in a complete way. Any help is appreciated. _________________________________________________________________ Share life as it happens with the new Windows Live. http://www.windowslive.com/share.html?ocid=TXT_TAGHM_Wave2_sharelife_122007

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how to compare elements of 2 lists
by sith . Jan. 4, 2008

Jan. 4, 2008

sith . wrote: > Hi, > I've read the posts on comparing 2 lists and couldn't find the answer to > my question. > I have 2 lists > a = [4,3,2,6,7,9] > b = [8,6,3,3,2,7] > How can I determine if the elements in a are larger or smaller than the > elements in b. > > for i in a: > for u in b: > i > u > does not return the result I seek. > > In this example, 4 from a is compared to 8,6,3,3,2,7 then 3 from a is > compared to all the elements in b. > I'd like > 4 to 8, > 3 to 6, > 2 to 3 and so on; like 2 columns in excel, the third column would be a > new list of boolean values. > Can someone help please? Thank you. > all(all(i>j for j in b) for i in a) HTH Hi, Thanks for your reply. This is what I get: >>> a = [4,3,2,6,7,9] >>> b = [8,6,3,3,2,7] >>> all(all(i>j for j in b) for i in a) >>> all(all(i>j for j in b) for i in a) False How do I make it loop through the whole list? --------------------------------- Never miss a thing. Make Yahoo your homepage.

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Learning about callbaks
by Michael Bernhard Arp Sørensen Jan. 2, 2008

Jan. 2, 2008

Hi there. I want to learn about callbacks because we use it at work in our software. I there a short "hello world"-like version of a callback example? -- Med venlig hilsen/Kind regards Michael B. Arp Sørensen Programmør / BOFH I am /root and if you see me laughing you better have a backup.

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Mobile Python
by Antonio Salgado Jan. 1, 2008

Jan. 1, 2008

Hello to everyone and wishing you all the best and succes in this new year!! Well i'm wondering if someone can point me out or help on this, I want to write apps for mobile devices, but for the regular nokia (like the 5300), but i haven't find documentation or anything. Hope someone can help me. My best wishes and greeting from Mexico!! -- Antonio Salgado Leiner. New Media, Blogger & Podcaster. syntax error in KITCHEN.H : COFFEE not found http://osound101.btpodshow.com/ http://blogmodelolight.com http://blogcoronamusicfest.com http://blogsocioaguila.com http://modeblog-light.blogspot.com http://rockampeonatotelcel.blogspot.com http://osound101.blogspot.com http://chocoaventura.blogspot.com http://mascherry.com http://blogmobalis.com http://blogpromocionestelcel.com http://blogreventour.com http://blogvictoria.com http://fritsi.com/DrOso http://droso.jaiku.com/ http://twitter.com/droso "mensaje escrito sin acentos para compatibilidad de formatos"

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Re: [Tutor] how to sort the data inside the file.
by Chris Fuller Dec. 31, 2007

Dec. 31, 2007

On Monday 31 December 2007 06:19, goldgod a wrote: > hello all, > Please find the attached file. I want to sort the content > of this file based on the "bytes" in descending order. How can i do > it, any pointers to it. This is a classic case for the use of regular expressions. A powerful tool, but can be tricky. I create a RE for a record, and than use the findall() function to get all of them in a list. I'll walk you through it. A not of caution: once you get the hang of REs, using them will leave you feeling giddy! Note: I load the whole file into memory and parse it in one piece. If your log is up in the megabytes, it might make more sense to read it in line by line. All of this is well documented in the Python Library Reference. The code: import re fd = open('test', 'r') s = fd.read() fd.close() # seperate into records lin = re.findall('\s*([^\s]+)\s+([^\s]+)\s+(\d+)( [kM])?bytes', s) # iterate through the records, and convert the text of the size to an integer for fields in lin: if fields[3] == ' M': mul = 1000000 #mul = 1024000 #mul = 1048576 elif fields[3] == ' k': mul = 1000 #mul = 1024 else: mul = 1 lout.append( (fields[0], fields[1], int(fields[2])*mul) ) # now sort lout.sort(lambda a,b: cmp(a[2], b[2])) Most of processing is happeneing in the single line lin = re.findall('\s*([^\s]+)\s+([^\s]+)\s+(\d+)( [kM])?bytes', s) Here is the regular expression '\s*([^\s]+)\s+([^\s]+)\s+(\d+)( [kM])?bytes' From left to right: \s* The \s designates whitespace, the asterisk matches zero or multiple instances. ([^\s]+) The parentheses designate a "group", which can be referenced later, and represents the hyphen delimited IP address. It also works in the familiar order-of-operations manner. We'll see this in the last piece, The square brackets designate a list of valid characters. The caret inside is an inversion: match anything that isn't in the set. \s designates whitespace, so this matches one or more characters of not-whitespace stuff. \s+ The plus matches one or multiple instances of whitespace. ([^\s]+) The second referenced group, which is the domain name in your file. \s+ matches the whitespace between fields (\d+) the third referenced ("matched") group, which is one or more decimal digits. ( [kM])? Now the tricky bit. The [kM] matches any character in the set, so either "k" or "M". The space inside the group includes the space preceeding the "k" or "M" and the ? applies to the whole group, and matches zero or one instance, which allows records that have only "bytes" to be matched. These will have None returned for that group, and " k" or " M" if these were present. bytes This is pretty obvious. Nothing funny going on here. I hope that made sense. The other tricky bit is the sort. In python, lists can be sorted in place, if you pass a function that determines the relative precedence of two elements. The cmp() built-in is a shorthand that makes this easy. What this line does is sorts the list according to the value of the third element. Reverse the a and b to get a descending sort. An interesting note: I mismatched some parentheses at first, and I ended up multiplying the string that converted to int rather than the int. Python will happily convert a million digit int for you, but damn it takes a long time! Cheers

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how to sort the data inside the file.
by goldgod a Dec. 31, 2007

Dec. 31, 2007

hello all, Please find the attached file. I want to sort the content of this file based on the "bytes" in descending order. How can i do it, any pointers to it. -- Thanks & Regards, goldgod

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