Programming :: Equivalence Classes Based On Field Values And Multi-key Hashtable?
May 12, 2010
I've got a set of objects (all of the same type). I'm trying to think of a good way to divide it into equivalence classes, with equivalence of two objects defined as meaning a specified set of attributes are equal for both objects. More concretely, I've got:
- a Java class with around 50 fields
- a bunch of instances of the class
I want:
- to divide the instances into a few sets
- in each set, each instance has field 1 - field 5 equal to fields 1-5 of the other instances in the set.
The method I've come up with is to generate a hashcode for each instance based on the hashcodes of fields 1-5*, and map the hashcode to one of my sets. Ignoring problems with potential hashcode collisions (which I'm expecting to be too rare to worry about for now), does that sound reasonable? It seems simple enough, but I'm wondering if there's a simpler method I haven't thought of.
* I'll generate the hashcode using a method based on Eclipse's generic hashcode method, which looks like this:
Code:
public int hashCode() {
final int prime = 31;
int result = 1;
I've had a very colorful morning learning the innerparts of Linux's sort command, and have come across yet another issue that I can't seem to find an answer for in the documentation. I'm currently using -t, to indicate that my fields are split by the comma character, but I'm finding that in some of my files, the comma is used (between double-quotes) within values:
Jonathan Sampson,,foo@bar.com,0987654321 "Foobar CEO,","CEO,",ceo@foobar.com,,
How can I use a comma to terminate my fields, but ignore the occurences of it within values? Is this fairly simple, or do I need to re-export all of my data using a more-foreign field-terminator? (Unfortunately, I do not have any control over declaring a different terminator with this particular project).
In my file there are 2 fields separated by space.Sample content of file are as follows:56060 154242 053030 0Now i want to check second field of the file and if all values in second field are 0(zero) and send mail containing all contents of the file
I am splitting a file based on the values read from an input file. The below one is the script.
1)How do I add the header which is present in the original file to the new split files created?(For eg. pharmacyf conatins header as table column names. The new files created (ODS.POS.$pharmacyid.$tablename.$CURRENT_DATE.dat) are without the header).
2) Also the script is creating 0 byte files for the pharmacyids which are not available in the intial file? Can this be avoided?
for pharmacyf in * do tablename=`echo $pharmacyf |cut -f4 -d'.' ` while read pharmacyid do grep -w $pharmacyid $pharmacyf >> $OUT/ODS.POS.$pharmacyid.$tablename.$CURRENT_DATE.dat done< inputfile done
I'm trying to display fields from flat files where the first 8 fields are always the same. Fields 9 - n are varied but will contain specific patterns I'm after. I'm using this so far because "mySearch" is on each line I want to examine.
Code:
How would you pattern match and include 2 additional fields above field $9 but change field position from line to line?
I am creating a game with random variables. In the game I have created a dialogue exchange to players. I have set up a table with various returns and I inserted {$fields} to represent various random variables. When I call on the requested fields, I only see the field text and my field names. Am I supposed to parse something and call it back another way?
ie: myfield is: "You have won {$random1} silver! <br />{$wi['gender'] majesty rewards you well." the code I am using to call that field is:
I want to select lines from FileA based on a key field in FileB.
egrep does this nicely: "egrep -w '0132874|0132880|0100765' < " FileA
Suppose FileB consists of three lines:
0132874 0132880 0100765
Is there a way to code egrep to do the selection? I really like code which does not use explicit loops so my interest is to find a grep or egrep or sed (or some other) command to perform this function.
Neither file is sorted on the key field but they could be. There is no requirement to keep the files in their present order.We may assume that each key value in each file is unique.
I have a lot of files with thousands of rows and usually two columns of data. Column 1 is a coordinate, column 2 is a score. I want to delete rows that have a value in column 2 over, in this case, 50.
I know the basic answer about how to create a class as ABC.But I don;'t know- - why I have to create a AbstractBaseClass. - In what situations it can be used.an example code base and not like a animal(base) and tiger(derived) relationship example.
This is probably a really stupid thing to ask considering the development I'm doing (effectivly creating a virus scanner), but how do I link classes/cpp files?I have 3 applications/sections that I can compile/combine with a makefile, that's fine, but I need them to run 1, 2, 3 once the output from the makefile is done.Currently the only section to actually run is whichever I have "main" in and obviously if I put that into all three, they won't compile as one.I've been looking all over the place at all sorts, header files and such, but there is no mention of how toually do this although I'm sure it must be possible. I'm used to being able to do this in Java and I'm sure I've seen C++ applications do it, but not worked out how.I have 3x .cpp files which are combined into one using a makefile:
Is it possible to have a templated c++ stl container in another class without specifying the type prior to compile time? I haven't coded in c++ in a while and im at a total loss.
For example - Not real code. Just outlining the problem code...
I am fairly new to c++. There must be a better way to do the following?:- Say I have a base class, Pet. I have several child classes that extend from this, like Dog, Cat, Fish etc.
I have the following function, that returns a pointer to a new Pet:- Code: Pet* addPetToVet() { //Do some stuff return new Pet(); } This will return a pointer an instance of a pet object.
Now, if I want to interpret this pet as a dog or cat I have to do this:- Code: Dog* dogA = static_cast<Dog*>(addPetToVet()); Cat* catA = static_cast<Cat*>(addPetToVet()); Is there a way around this? Casting seems lame. I cant write a function for each type of pet.
I'm new to Java. I'm trying to use some dynamically loaded classes in my application. The application doesn't know those classes , Just it try to load a class by name that its name came from input. It doesn't know class (So I can't use casting) but just needs to call some methods of that class (every class should have that methods). I thought about interfaces but I don't know how. How can I call those methods?
Why are the 'defense' method calls actually using the 'offense' methods.Also, is there a way to remove the commented base classes for 'Player' so that the casting isn't necessary?
I'm trying to use awk to remove rows that are duplicates based on 3 fields, and I want to keep the on that has the higher value in another field. I'm working in C-Shell. For example the below is greped out of a larger data set to use in here as example:
Does anyone know of an alsa based software multi-band (10 or more) graphic audio frequency equalizer that works with Suse 11.x? To be clear, I don't mean an equalizer within an audio or video player. One that can be used with any sound application, that works between the output of the player and the output plugs on a motherboard or sound card.
I want to validate a web form using PHP. I spent ages confusing myself with client side scripting and realised until I worked out it is not what I want. My problem is that now I am looking at PHP and everything is mixed up in my brain. I need to point out that PHP is very new to me! This is what I already have: 1 An html page with my form on it. 2 PHP page which emails the contents of the form to me.
The above works well. For the sake of clarity, here are my pages (cut down to the essentials where appropriate): My html form: first name surname Email Home phone Mobile Work phone
I have read and understood your terms and conditions. My php script (regform.php) $receiver = 'me@email'; $subject = 'New registration'; #$message = 'This is a new registration.'; $surname = $_POST['surname']; $firstname = $_POST['firstname']; $address = $_POST['address']; $email = $_POST['email']; $homeph = $_POST['homeph']; $mobileph = $_POST['mobileph']; $workph = $_POST['workph']; $time = $_POST['time']; #from here $oldaddress = $_POST['oldaddress']; $DOB = $_POST['DOB']; $elect = $_POST['elect']; $job = $_POST['job']; $salary = $_POST['salary']; $employer = $_POST['employer']; $benefit = $_POST['benefit']; $smoke = $_POST['smoke']; $claim = $_POST['claim']; $children = $_POST['children']; $children2 = $_POST['children2']; $pets = $_POST['pets']; $pets2 = $_POST['pets2']; $require = $_POST['require']; $terms = $_POST['terms']; $rooms = $_POST['rooms']; $body = "first name:$firstname surname:$surname DOB:$DOB email:$email home phone:$homeph mobile phone:$mobileph work phone:$workph address: $address time at this address:$time previous address:$oldaddress electoral register:$elect employment:$job employer:$employer salary:$salary benefit claim:$benefit future benefit:$claim children:$children ages:$children2 pets:$pet pet type:$pets2 other requirements:$require terms:$terms"; $headers = 'From: email' . " " . 'Reply-To: email " " . 'X-Mailer: PHP/' . phpversion(); mail($receiver, $subject, $body, $headers, "From: $firstname $surname " . "Reply-To: $firstname $surname class="inlineimg" />;
You can see there are many more form fields than I have shown in my example html form above. What I want is that the following fields have to be filled: 1 mobileph 2 email 3 terms (checkbox) I would like the user to be asked to fill the form in properly if any/all of the 3 fields have not been filled in. I imagine I need some php in the html page and some more in the php page. I am certainly not asking any one to do this for me but I am really confused. I have googled and copied and pasted and edited for 6 hours and I am lost. What I want is a very simple and clear example of the code needed. Sorry if I sound as if I can't search properly on Google: in this case I clearly can't!
how do i ask in a query for any numeric or string field? It may not have any meaning, but i need it to fill a toplink DataReadQuery in java....Something like " select * from table where table.fieldA='?'
I'm having a bit of a trouble getting a particular field replaced in a host list. I have a MasterHostList which has a comma delimiter for fields and a new line to separate servers.
I then have a file.list file with a grouping of server names. What I need is to search the MasterHostList and for each server that is in the file.list I need to change the fourth field from group1 to group2 without changing the order or position of anything in the MasterHostList. Obviously the above names are arbitrary.
Failed attempts have been: for SERVER in `cat file.list`; do sed /$SERVER/s/,group1,/,group2,/ MasterHostList MasterHostList.tmp && mv -f MasterHostList.tmp MasterHostList; done for SERVER in `cat file.list`;do awk 'BEGIN { FS=OFS="," } /^${SERVER}/ { $4 = "group2" } 1' ./MasterHostList MasterHostList.tmp && mv -f MasterHostList.tmp MasterHostList; done
Both of these would in various output tests find the correct lines, but it wouldn't change them all correctly.
The first field identifies the file name, the second is the search key, and the third is the line number of the file that the search key points to. Any subsequent fields are other key/line number pairs.
As an example, I can search for 4151 (key) from my bash script to identify the file I will have to access, but I also need to capture the line (142) as well, and I can't figure out how to do that using grep, awk or sed (or anything else).
If I have a MySQL field called, say, "Occupation", which contains "Java Programmer" in it, I would like it to come up when I search for "Java", so that I can get to the other fields in the table. How do I do this?
In the MySQL database for one of my programming projects, I used a "YEAR(4)", because I wanted the column to contain four-digit year values. I discovered, though, that this type only allows values from 1901 to 2155, which is not workable as some year values are previous to the twentieth century. But I do not want a "DATE" type because the month and day are of no interest to me. What type should I convert to that would be the least radical change in data type, while giving more range?
The thing is that the command for sed resembles the following
[code]...
Now if I want to place another command like grep or cut in the address field how do I do it. Actually I don't know the line number. The user has to give it as an input. How shall I do that?
Is there a list somewhere that shows what programs for Fedora are the equivalence for Windows? I know that OpenOffice is the equivalence for Office but what else.
I am in the process of learning some scripting, however I am running into a roadblock in specifying a certain time format in the array. Ideally I would like to use Here are the lines of text that I am interrogating:
Using content proposal in helios, giving problem if u press tab. Below is the error. For recreation snippet is provided(taken from 2 sites) after error log.Only u need to press tab while proposal pop up is visible & then point mouse at client.
#################################ERROR LOG############################# # A fatal error has been detected by the Java Runtime Environment: #
