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  • Python: Beginning problems

    - by Blogger
    ok so basically i very new to programming and have no idea how to go about these problems help if you will ^^ Numerologists claim to be able to determine a person’s character traits based on the “numeric value” of a name. The value of a name is determined by summing up the values of the letters of the name, where ‘a’ is 1, ‘b’ is 2, ‘c’ is 3 etc., up to ‘z’ being 26. For example, the name “Zelle” would have the value 26 + 5 + 12 + 12 + 5 = 60 (which happens to be a very suspicious number, by the way). Write a program that calculates the numeric value of a single name provided as input. Word count. A common utility on Unix/Linux systems is a small program called “wc”. This program counts the number of lines, words (strings of characters separated by blanks, tabs, or new lines), and characters in a file. Write your own version of this program. The program should accept a file name as input and then print three numbers showing the count of lines, words, and characters in the file.

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  • Good FORTRAN books/tutorials for beginners?

    - by AndrejaKo
    This may be a duplicate of http://stackoverflow.com/questions/31672/learning-fortran-in-the-modern-era, but that thread went on discussing legacy code concerns. Anyway, few months ago in a bookstore sale I picked up book called FORTRAN 66 for PDP-11. I found it interesting and decided it would be nice to learn FORTRAN. So I'm looking for some modern books/tutorials dealing with new versions of FORTRAN.

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  • Mysql Text Storage?

    - by mii
    I was wondering if you where to have an article or articles with huge amounts of text, what would be better when creating the database structure for the articles text? And why? What will be the advantages or disadvantages if any?. I was thinking of using one of the data types below to hold the articles text for the MySQL database. VARCHAR TEXT MEDIUMTEXT LONGTEXT

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  • Can this PHP version of SPICE be improved?

    - by Noctis Skytower
    I do not know much about PHP's standard library of functions and was wondering if the following code can be improved in any way. The implementation should yield the same results, the API should remain as it is, but ways to make is more PHP-ish would be greatly appreciated. This is a custom encryption library. Code <?php /*************************************** Create random major and minor SPICE key. ***************************************/ function crypt_major() { $all = range("\x00", "\xFF"); shuffle($all); $major_key = implode("", $all); return $major_key; } function crypt_minor() { $sample = array(); do { array_push($sample, 0, 1, 2, 3); } while (count($sample) != 256); shuffle($sample); $list = array(); for ($index = 0; $index < 64; $index++) { $b12 = $sample[$index * 4] << 6; $b34 = $sample[$index * 4 + 1] << 4; $b56 = $sample[$index * 4 + 2] << 2; $b78 = $sample[$index * 4 + 3]; array_push($list, $b12 + $b34 + $b56 + $b78); } $minor_key = implode("", array_map("chr", $list)); return $minor_key; } /*************************************** Create the SPICE key via the given name. ***************************************/ function named_major($name) { srand(crc32($name)); return crypt_major(); } function named_minor($name) { srand(crc32($name)); return crypt_minor(); } /*************************************** Check validity for major and minor keys. ***************************************/ function _check_major($key) { if (is_string($key) && strlen($key) == 256) { foreach (range("\x00", "\xFF") as $char) { if (substr_count($key, $char) == 0) { return FALSE; } } return TRUE; } return FALSE; } function _check_minor($key) { if (is_string($key) && strlen($key) == 64) { $indexs = array(); foreach (array_map("ord", str_split($key)) as $byte) { foreach (range(6, 0, 2) as $shift) { array_push($indexs, ($byte >> $shift) & 3); } } $dict = array_count_values($indexs); foreach (range(0, 3) as $index) { if ($dict[$index] != 64) { return FALSE; } } return TRUE; } return FALSE; } /*************************************** Create encode maps for encode functions. ***************************************/ function _encode_map_1($major) { return array_map("ord", str_split($major)); } function _encode_map_2($minor) { $map_2 = array(array(), array(), array(), array()); $list = array(); foreach (array_map("ord", str_split($minor)) as $byte) { foreach (range(6, 0, 2) as $shift) { array_push($list, ($byte >> $shift) & 3); } } for ($byte = 0; $byte < 256; $byte++) { array_push($map_2[$list[$byte]], chr($byte)); } return $map_2; } /*************************************** Create decode maps for decode functions. ***************************************/ function _decode_map_1($minor) { $map_1 = array(); foreach (array_map("ord", str_split($minor)) as $byte) { foreach (range(6, 0, 2) as $shift) { array_push($map_1, ($byte >> $shift) & 3); } } return $map_1; }function _decode_map_2($major) { $map_2 = array(); $temp = array_map("ord", str_split($major)); for ($byte = 0; $byte < 256; $byte++) { $map_2[$temp[$byte]] = chr($byte); } return $map_2; } /*************************************** Encrypt or decrypt the string with maps. ***************************************/ function _encode($string, $map_1, $map_2) { $cache = ""; foreach (str_split($string) as $char) { $byte = $map_1[ord($char)]; foreach (range(6, 0, 2) as $shift) { $cache .= $map_2[($byte >> $shift) & 3][mt_rand(0, 63)]; } } return $cache; } function _decode($string, $map_1, $map_2) { $cache = ""; $temp = str_split($string); for ($iter = 0; $iter < strlen($string) / 4; $iter++) { $b12 = $map_1[ord($temp[$iter * 4])] << 6; $b34 = $map_1[ord($temp[$iter * 4 + 1])] << 4; $b56 = $map_1[ord($temp[$iter * 4 + 2])] << 2; $b78 = $map_1[ord($temp[$iter * 4 + 3])]; $cache .= $map_2[$b12 + $b34 + $b56 + $b78]; } return $cache; } /*************************************** This is the public interface for coding. ***************************************/ function encode_string($string, $major, $minor) { if (is_string($string)) { if (_check_major($major) && _check_minor($minor)) { $map_1 = _encode_map_1($major); $map_2 = _encode_map_2($minor); return _encode($string, $map_1, $map_2); } } return FALSE; } function decode_string($string, $major, $minor) { if (is_string($string) && strlen($string) % 4 == 0) { if (_check_major($major) && _check_minor($minor)) { $map_1 = _decode_map_1($minor); $map_2 = _decode_map_2($major); return _decode($string, $map_1, $map_2); } } return FALSE; } ?> This is a sample showing how the code is being used. Hex editors may be of help with the input / output. Example <?php # get and process all of the form data @ $input = htmlspecialchars($_POST["input"]); @ $majorname = htmlspecialchars($_POST["majorname"]); @ $minorname = htmlspecialchars($_POST["minorname"]); @ $majorkey = htmlspecialchars($_POST["majorkey"]); @ $minorkey = htmlspecialchars($_POST["minorkey"]); @ $output = htmlspecialchars($_POST["output"]); # process the submissions by operation # CREATE @ $operation = $_POST["operation"]; if ($operation == "Create") { if (strlen($_POST["majorname"]) == 0) { $majorkey = bin2hex(crypt_major()); } if (strlen($_POST["minorname"]) == 0) { $minorkey = bin2hex(crypt_minor()); } if (strlen($_POST["majorname"]) != 0) { $majorkey = bin2hex(named_major($_POST["majorname"])); } if (strlen($_POST["minorname"]) != 0) { $minorkey = bin2hex(named_minor($_POST["minorname"])); } } # ENCRYPT or DECRYPT function is_hex($char) { if ($char == "0"): return TRUE; elseif ($char == "1"): return TRUE; elseif ($char == "2"): return TRUE; elseif ($char == "3"): return TRUE; elseif ($char == "4"): return TRUE; elseif ($char == "5"): return TRUE; elseif ($char == "6"): return TRUE; elseif ($char == "7"): return TRUE; elseif ($char == "8"): return TRUE; elseif ($char == "9"): return TRUE; elseif ($char == "a"): return TRUE; elseif ($char == "b"): return TRUE; elseif ($char == "c"): return TRUE; elseif ($char == "d"): return TRUE; elseif ($char == "e"): return TRUE; elseif ($char == "f"): return TRUE; else: return FALSE; endif; } function hex2bin($str) { if (strlen($str) % 2 == 0): $string = strtolower($str); else: $string = strtolower("0" . $str); endif; $cache = ""; $temp = str_split($str); for ($index = 0; $index < count($temp) / 2; $index++) { $h1 = $temp[$index * 2]; if (is_hex($h1)) { $h2 = $temp[$index * 2 + 1]; if (is_hex($h2)) { $cache .= chr(hexdec($h1 . $h2)); } else { return FALSE; } } else { return FALSE; } } return $cache; } if ($operation == "Encrypt" || $operation == "Decrypt") { # CHECK FOR ANY ERROR $errors = array(); if (strlen($_POST["input"]) == 0) { $output = ""; } $binmajor = hex2bin($_POST["majorkey"]); if (strlen($_POST["majorkey"]) == 0) { array_push($errors, "There must be a major key."); } elseif ($binmajor == FALSE) { array_push($errors, "The major key must be in hex."); } elseif (_check_major($binmajor) == FALSE) { array_push($errors, "The major key is corrupt."); } $binminor = hex2bin($_POST["minorkey"]); if (strlen($_POST["minorkey"]) == 0) { array_push($errors, "There must be a minor key."); } elseif ($binminor == FALSE) { array_push($errors, "The minor key must be in hex."); } elseif (_check_minor($binminor) == FALSE) { array_push($errors, "The minor key is corrupt."); } if ($_POST["operation"] == "Decrypt") { $bininput = hex2bin(str_replace("\r", "", str_replace("\n", "", $_POST["input"]))); if ($bininput == FALSE) { if (strlen($_POST["input"]) != 0) { array_push($errors, "The input data must be in hex."); } } elseif (strlen($bininput) % 4 != 0) { array_push($errors, "The input data is corrupt."); } } if (count($errors) != 0) { # ERRORS ARE FOUND $output = "ERROR:"; foreach ($errors as $error) { $output .= "\n" . $error; } } elseif (strlen($_POST["input"]) != 0) { # CONTINUE WORKING if ($_POST["operation"] == "Encrypt") { # ENCRYPT $output = substr(chunk_split(bin2hex(encode_string($_POST["input"], $binmajor, $binminor)), 58), 0, -2); } else { # DECRYPT $output = htmlspecialchars(decode_string($bininput, $binmajor, $binminor)); } } } # echo the form with the values filled echo "<P><TEXTAREA class=maintextarea name=input rows=25 cols=25>" . $input . "</TEXTAREA></P>\n"; echo "<P>Major Name:</P>\n"; echo "<P><INPUT id=textbox1 name=majorname value=\"" . $majorname . "\"></P>\n"; echo "<P>Minor Name:</P>\n"; echo "<P><INPUT id=textbox1 name=minorname value=\"" . $minorname . "\"></P>\n"; echo "<DIV style=\"TEXT-ALIGN: center\"><INPUT class=submit type=submit value=Create name=operation>\n"; echo "</DIV>\n"; echo "<P>Major Key:</P>\n"; echo "<P><INPUT id=textbox1 name=majorkey value=\"" . $majorkey . "\"></P>\n"; echo "<P>Minor Key:</P>\n"; echo "<P><INPUT id=textbox1 name=minorkey value=\"" . $minorkey . "\"></P>\n"; echo "<DIV style=\"TEXT-ALIGN: center\"><INPUT class=submit type=submit value=Encrypt name=operation> \n"; echo "<INPUT class=submit type=submit value=Decrypt name=operation> </DIV>\n"; echo "<P>Result:</P>\n"; echo "<P><TEXTAREA class=maintextarea name=output rows=25 readOnly cols=25>" . $output . "</TEXTAREA></P></DIV></FORM>\n"; ?>

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  • Python beginer having trouble running code

    - by Protean
    For some reason this code will not seem to run in the interpreter. When I hit F5 nothing happens, not even the debugger seems to recognize it. I assume it has something to do with the class, as when removed the interpreter seems to recognize the rest of the code. Please tell me what I am doing wrong. Edit: I have restarted the interpreter multiple times, any other piece of code I try to load runs fine, just this one is having trouble. print ('Why won't this work?') class sorting_class: def __init__(self): self.order = ['a', 'b', 'c', 'd'] self.globali = 0 self.orderi = 0 self.sortedlist = [] def sort(self, array): carry, leave = [] for arrayi in array: print ('run', arrayi) if self.order[self.orderi] == arrayi[self.globali]: carry.append(arrayi) else: if self.globali != 0: leave.append(arrayi) return carry, leave def srt(self, array): globalii = 0 carry, leave = my.sort(array) while len(self.sortedlist) != len(array): if len(self.carry) == 1: self.sortedlist.append(carry) arrayt = leave self.globali = 1 self.orderi = 0 carry, leave = my.sort(arrayt) elif len(self.carry) == 0: if len(self.leave) != 0: arrayt = leave self.globali = 1 self.orderi += 1 my.sort(arrayt) else: self.arrayt globalii += 1 self.orderi = globalii self.globali = 0 my.sort(arrayt) self.orderi = 0 else: arrayt = carry carry = [] self.globali += 1 carry, leave += my.sort(arrayt) my = sorting_class() x = ['ac', 'bc' ,'ab', 'da'] my.srt(x)

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  • Does C# support inner classes? [closed]

    - by Amy
    Possible Duplicates: Using Inner classes in C# Inner classes in C# Class declared inside of another class in C# Does C# support the concept of inner classes? If so, what are the benefits? Could someone please explain this to me?

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  • Python regex on list

    - by Peter Nielsen
    Hi there I am trying to build a parser and save the results as an xml file but i have problems.. For instance i get a TypeError: expected string or buffer when i try to run the code.. Would you experts please have a look at my code ? import urllib2, re from xml.dom.minidom import Document from BeautifulSoup import BeautifulSoup as bs osc = open('OSCTEST.html','r') oscread = osc.read() soup=bs(oscread) doc = Document() root = doc.createElement('root') doc.appendChild(root) countries = doc.createElement('countries') root.appendChild(countries) findtags1 = re.compile ('<h1 class="title metadata_title content_perceived_text(.*?)</h1>', re.DOTALL | re.IGNORECASE).findall(soup) findtags2 = re.compile ('<span class="content_text">(.*?)</span>', re.DOTALL | re.IGNORECASE).findall(soup) for header in findtags1: title_elem = doc.createElement('title') countries.appendChild(title_elem) header_elem = doc.createTextNode(header) title_elem.appendChild(header_elem) for item in findtags2: art_elem = doc.createElement('artikel') countries.appendChild(art_elem) s = item.replace('<P>','') t = s.replace('</P>','') text_elem = doc.createTextNode(t) art_elem.appendChild(text_elem) print doc.toprettyxml()

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  • Why the "mutable default argument fix" syntax is so ugly, asks python newbie

    - by Cawas
    Now following my series of "python newbie questions" and based on another question. Go to http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#other-languages-have-variables and scroll down to "Default Parameter Values". There you can find the following: def bad_append(new_item, a_list=[]): a_list.append(new_item) return a_list def good_append(new_item, a_list=None): if a_list is None: a_list = [] a_list.append(new_item) return a_list So, question here is: why is the "good" syntax over a known issue ugly like that in a programming language that promotes "elegant syntax" and "easy-to-use"? Why not just something in the definition itself, that the "argument" name is attached to a "localized" mutable object like: def better_append(new_item, a_list=[].local): a_list.append(new_item) return a_list I'm sure there would be a better way to do this syntax, but I'm also almost positive there's a good reason to why it hasn't been done. So, anyone happens to know why?

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  • Does a C# using statement perform try/finally?

    - by Lirik
    Suppose that I have the following code: private void UpdateDB(QuoteDataSet dataSet, Strint tableName) { using(SQLiteConnection conn = new SQLiteConnection(_connectionString)) { conn.Open(); using (SQLiteTransaction transaction = conn.BeginTransaction()) { using (SQLiteCommand cmd = new SQLiteCommand("SELECT * FROM " + tableName, conn)) { using (SQLiteDataAdapter sqliteAdapter = new SQLiteDataAdapter()) { sqliteAdapter.Update(dataSet, tableName); } } transaction.Commit(); } } } The C# documentation states that with a using statement the object within the scope will be disposed and I've seen several places where it's suggested that we don't need to use try/finally clause. I usually surround my connections with a try/finally, and I always close the connection in the finally clause. Given the above code, is it reasonable to assume that the connection will be closed if there is an exception?

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  • Dealing with multiple Javascript IF statements.

    - by Joey
    Is it possible to put multiple IF statements in Javascript? If so, I'm having a fair amount of trouble with the statement below. I was wondering if you can put another IF statement in between if (data == 'valid') AND else? I want to add another if data =='concept') between the two. if (data == 'valid') { $("#file").slideUp(function () { $("#file").before('<div class="approvedMessage">WIN WIN WIN!</div>'); setTimeout(ApprovedProof, 5000); }); function ApprovedProof() { $("#file").slideDown(); $('.approvedMessage').fadeOut(); } } else { $("#file").slideUp(function () { $("#file").before('<div class="deniedMessage">NO NO NO!</div>'); setTimeout(DeniedProof, 5000); }); function DeniedProof() { $("#file").slideDown(); $('.deniedMessage').fadeOut(); } }

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  • Why doesn't 'Q' unify in this PROLOG program

    - by inspectorG4dget
    Hello SO, I am writing a PROLOG program in which the variable of interest (Q) refuses to unify. I have gotten around this with a hacky solution (include a write statement). But there has to be a way to make this unify, but for the love of me, I am not able to figure it out. I'd really appreciate any help. Thanks in advance. Here is my code (I have annotated wherever I have excluded code for brevity) :- use_module(library(bounds)). :- use_module(library(lists)). solve([17],Q,_,_,_):- write(Q). %this is the hacky workaround solve(L,Q,1,3,2) :- jump(L,Q,N,1,3,2,R), solve(N,R,S,D,M), member([S|[D|[M|[]]]],[[1, 3, 2], [1, 9, 4], [2, 10, 5] this list contains 76 items - all of which are lists of length 3. I have omitted them here for the sake of brevity]). % there are about 75 other definitions for solve, all of which are structured exactly the same. The only difference is that the numbers in the input parameters will be different in each definition jump(L,Q,N,S,D,M,R):- member(S,L), not(member(D,L)), member(M,L), delete(L,S,X), delete(X,M,Y), append(Y,[D],N), append(Q,[[S,D]],R). cross_sol(Q) :- solve([5,9,10,11,17,24],[],S,D,M), member([S,D,M], [ I have edited out this list here for the sake of brevity. It is the same list found in the definition of solve ]). For some reason, Q does not unify. Please help!

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  • Python doesn't work properly when I execute a script after using Right Click >> Command Prompt Here

    - by Dominic Bou-Samra
    This is a weird bug. I know it's something funky going on with my PATH variable, but no idea how to fix it. If I have a script C:\Test\test.py and I execute it from within IDLE, it works fine. If I open up Command Prompt using Runcmd.exe and navigate manually it works fine. But if I use Windows 7's convenient Right Click on folder Command Prompt Here then type test.py it fails with import errors. I also cannot just type "python" to reach a python shell session if I use the latter method above. Any ideas?

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  • Java: 2-assignments-2-initializations inside for-loop not allowed?

    - by HH
    $ javac MatchTest.java MatchTest.java:7: ')' expected for((int i=-1 && String match="hello"); (i=text.indexOf(match)+1);) ^ MatchTest.java:7: ';' expected for((int i=-1 && String match="hello"); (i=text.indexOf(match)+1);) ^ MatchTest.java:7: ';' expected for((int i=-1 && String match="hello"); (i=text.indexOf(match)+1);) ^ MatchTest.java:7: not a statement for((int i=-1 && String match="hello"); (i=text.indexOf(match)+1);) ^ MatchTest.java:7: illegal start of expression for((int i=-1 && String match="hello"); (i=text.indexOf(match)+1);) ^ 5 errors $ cat MatchTest.java import java.util.*; import java.io.*; public class MatchTest { public static void main(String[] args){ String text = "hello0123456789hello0123456789hello1234567890hello3423243423232"; for((int i=-1 && String match="hello"); (i=text.indexOf(match)+1);) System.out.println(i); } }

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  • Validating age field

    - by Marcelo
    Hi people, I'm trying to validate an age field in a form but I'm having some problem. First I tried to make sure that the field will not be send empty. I don't know JavaScript so I searched some scripts and adapted them to this: function isInteger (s) { var i; if (isEmpty(s)) if (isInteger.arguments.length == 1) return 0; else return (isInteger.arguments[1] == true); for (i = 0; i < s.length; i++) { var c = s.charAt(i); if (!isDigit(c)) return false; } return true; } function isEmpty(s) { return ((s == null) || (s.length == 0)) } function validate_required(field,alerttxt) { with (field) { if (value==null||value=="") { alert(alerttxt);return false; } else { return true; } } } function validate_form(thisform) { with (thisform) { if ((validate_required(age,"Age must be filled out!")==false) || isInteger(age,"Age must be and int number")==false)) {email.focus();return false;} } } //html part <form action="doador.php" onsubmit="return validate_form(this)" method="post"> It's working fine for empty fields, but if I type any letters or characters in age field, it'll be sent and saved a 0 in my database. Can anyone help me? Sorry for any mistake in English, and thanks in anvance for your help.

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  • What does the '&' operator do in C++?

    - by rascher
    n00b question. I am a C guy and I'm trying to understand some C++ code. I have the following function declaration: int foo(const string &myname) { cout << "called foo for: " << myname << endl; return 0; } How does the function signature differ from the equivalent C: int foo(const char *myname) Is there a difference between using string *myname vs string &myname? What is the difference between & in C++ and * in C to indicate pointers? Similarly: const string &GetMethodName() { ... } What is the & doing here? Is there some website that explains how & is used differently in C vs C++?

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  • BlueJ Chpt 4 - Auction Project - How to make removeLot method work after entering a new lot

    - by Ellaine Ryan
    Hi All I am learning Java through BlueJ I would like to add a removeLot method to the Auction Class in BlueJ Chpt 4. This involves also returning the lot with the given number or null if there is no such lot. If you enter , say 5 lots and then use the remove method, this codes removes whichever lot you specify. However if you enter a new lot after using the removeLot method - an internal error message comes up regarding lotnumbering . Any ideas? Thanks Elaine public Lot removeLot(int number) { if((number >= 1) ) { } Lot lot = getLot (number); if(lot !=null) { lots.remove(lot); } return lot; }

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  • strange error in haskell about indentation of if-then-else

    - by Drakosha
    I have the following code: foo :: Int -> [String] -> [(FilePath, Integer)] -> IO Int foo _ [] _ = return 4 foo _ _ [] = return 5 foo n nameREs pretendentFilesWithSizes = do result <- (bar n (head nameREs) pretendentFilesWithSizes) if result == 0 then return 0 -- <========================================== here is the error else foo n (tail nameREs) pretendentFilesWithSizes I get an error on the line with the comment above, the error is: aaa.hs:56:2: parse error (possibly incorrect indentation) I'm working with emacs, there's no spaces, and i do not understand what did i do wrong.

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  • Python begineer confused by a piece of code

    - by Protean
    I understand the gist of the code, that it forms permutations; however, I was wondering if someone could explain exactly what is going on in the return statement. def perm(l): sz = len(l) print (l) if sz <= 1: print ('sz <= 1') return [l] return [p[:i]+[l[0]]+p[i:] for i in range(sz) for p in perm(l[1:])]

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  • SQLAlchemy unsupported type error - and table design issues?

    - by Az
    Hi there, back again with some more SQLAlchemy shenanigans. Let me step through this. My table is now set up as so: engine = create_engine('sqlite:///:memory:', echo=False) metadata = MetaData() students_table = Table('studs', metadata, Column('sid', Integer, primary_key=True), Column('name', String), Column('preferences', Integer), Column('allocated_rank', Integer), Column('allocated_project', Integer) ) metadata.create_all(engine) mapper(Student, students_table) Fairly simple, and for the most part I've been enjoying the ability to query almost any bit of information I want provided I avoid the error cases below. The class it is mapped from is: class Student(object): def __init__(self, sid, name): self.sid = sid self.name = name self.preferences = collections.defaultdict(set) self.allocated_project = None self.allocated_rank = 0 def __repr__(self): return str(self) def __str__(self): return "%s %s" %(self.sid, self.name) Explanation: preferences is basically a set of all the projects the student would prefer to be assigned. When the allocation algorithm kicks in, a student's allocated_project emerges from this preference set. Now if I try to do this: for student in students.itervalues(): session.add(student) session.commit() It throws two errors, one for the allocated_project column (seen below) and a similar error for the preferences column: sqlalchemy.exc.InterfaceError: (InterfaceError) Error binding parameter 4 - probably unsupported type. u'INSERT INTO studs (sid, name, allocated_rank, allocated_project) VALUES (?, ?, ?, ?, ?, ?, ?)' [1101, 'Muffett,M.', 1, 888 Human-spider relationships (Supervisor id: 123)] If I go back into my code I find that, when I'm copying the preferences from the given text files, it actually refers to the Project class which is mapped to a dictionary, using the unique project id's (pid) as keys. Thus, as I iterate through each student via their rank and to the preferences set, it adds not a project id, but the reference to the project id from the projects dictionary. students[sid].preferences[int(rank)].add(projects[int(pid)]) Now this is very useful to me since I can find out all I want to about a student's preferred projects without having to run another check to pull up information about the project id. The form you see in the error has the object print information passed as: return "%s %s (Supervisor id: %s)" %(self.proj_id, self.proj_name, self.proj_sup) My questions are: I'm trying to store an object in a database field aren't I? Would the correct way then, be copying the project information (project id, name, etc) into its own table, referenced by the unique project id? That way I can just have the project id field for one of the student tables just be an integer id and when I need more information, just join the tables? So and so forth for other tables? If the above makes sense, then how does one maintain the relationship with a column of information in one table which is a key index on another table? Does this boil down into a database design problem? Are there any other elegant ways of accomplishing this? Apologies if this is a very long-winded question. It's rather crucial for me to solve this, so I've tried to explain as much as I can, whilst attempting to show that I'm trying (key word here sadly) to understand what could be going wrong.

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