At work we have a txt file with items recorded in them
The columns are typical of
Apple, *fruit
Cow, *animal
House, *thing
Tree, *plant
Is it possible too read through this txt file to check if apple already exists. I namely want to build a preventative for adding double items...
I think you have to read the file in to a list of objects.
In this case, the object will get 2 properties: Type and Category.
After that you can easily perform comparisons etc on the list itself.
Edit:
Some stuff for you to read;
Reading a file: http://msdn.microsoft.com/en-us/library/system.io.streamreader.readline.aspx
Dictionary: http://msdn.microsoft.com/en-us/library/xfhwa508.aspx
I'm unable to write down an example now, but those are the ingredients.
Related
I am making an app that lets the user draw on the screen in different colors and brush sizes. I am storing the info about each drawn path in a JSON file once it has been drawn to keep it out of memory. Right now I have it parsing all existing paths, then adding the new one in and writing it all back out again. I want it to simply append the new data into the JSON file without having to read it in and parse it first, that will make it so only one path is ever in memory at a time.
I am using SBJSON, the JSONWriter has a few append functions but I think you need to have the JSON string to append it to first, not the file, meaning I would have to read in the file anyway. Is there a way to do this without reading in the file at all? I know exactly how the data is structured.
It's possible, but you have to cheat a little. You can just create a stand-alone JSON document per path, and append that to the file. So you'll have something like this in your file:
{"name":"path1", "from": [0,3], "to":[3, 9]}
{"name":"path2", "from": [0,3], "to":[3, 9]}
{"name":"path3", "from": [0,3], "to":[3, 9]}
Note that this is not ONE JSON document but THREE. Handily, however, SBJsonStreamParser supports reading multiple JSON documents in one go. Set the supportMultipleDocuments property and plug it into a SBJsonStreamParserAdapter, and off you go. This also has the benefit that if you have many, many paths in your file as you can start drawing before you're finished reading the whole file. (Because you get a callback for each path.)
You can see some information on the use case here.
I'm pretty sure its not possible...what I ended up doing was reading in the JSON file as a string then instead of wasting memory changing all that into Dictionaries and Arrays, I just looked for an instance of part of the string (ex: i wanted to insert something before the string "], "texts"" showed up) where I wanted to insert data and inserted it there and wrote it back out to file.
As far as I can tell this is the best solution.
I'm currently trying to implement some kind of search system in a program of mine, and wanted to use an index, but I'm fairly new at Objective-C. The main idea is to have a 'search' command or text box and when I type a word, it'll show me all the items that include that word. All these 'items' will be listed in a .txt file (hopefully) in alphabetical order. Any help is appreciated.
You need to read the .txt file into an NSSet or some other collection class and you can then search it using something like:
[words filterUsingPredicate:[NSPredicate predicateWithFormat:#"SELF contains[c] 'word'"]];
(See the Predicate Guide for details).
The ideal thing, if the text file is large and you want to index by the leading characters of each entry, is to create a "dope vector" of sorts, where each entry in the dope vector contains the first few characters of the line, followed by the file offset where the line starts. Note that one dope vector entry can cover a number of file lines, since it's just serving like the index tabs in a dictionary.
But if you want to search for words within a line in your file, you're better off using a SQL database, or some KWIC scheme.
I have an NSData that was created by using NSKeyedArchiver. Is there a way to iterate over all the values inside it? It must somehow be possible to get all the keys that were stored in it when using +[NSKeyedUnarchiver unarchiveObjectWithData:].
Thanks
A NSKeyedArchived file "simply" is a property list. You would need to find out the structure of that plist, though.
I found the source code of Cocotron very helpful one day, as I tried to decode some NSKeyedUnarchived data: http://code.google.com/p/cocotron/source/browse/Foundation/NSKeyedArchiving/NSKeyedUnarchiver.m (Maybe look at line 39 (initForReadingWithData:) which is called by unarchiveObjectWithData: (line #164)).
Maybe you can find out more about the archived objects that way.
I'm a noob right now with pygame and I was wondering how to load a textfile, then strip that into a a single line. I believe that i would need to use the .rstrip('/n') function on my variable with the openned text file. But now, how do I turn this into a list? If I intentionally used two colons (::) to separate between my relevant pieces of information in the text file, how do I make it into a list with each list index being the contents in between two sets of ::? The purpose is to create save files in a menu GUI when closed, so is there a simpler way to save and open the contents of variables from one instance of the program to the next?
>>> "foo::bar::baz".split("::")
['foo', 'bar', 'baz']
If you just want to save structured data, however, you might want to look at either the pickle or json libraries. Both of them give ways to dump Python objects to files and then load them back out again.
I started working on a new home project, I need to index specific files names with there paths.
The program will index files on my local hard-disk with no need to deal with the contents of the files (so I assuming/hoping it would be simple implementation).
At first the user will insert a list of file extensions to get indexed (During setup time).
Then the program will run and create the data structure holding the path for the specific file entered by the user.
Retrieving data from by data structure would look like this:
path of the file on my HDD=function(filename entered by user)
I thought about it for quite a while and wrote a design for the data structure here is my suggestion
(Design Illustration):
I'll use an array with a hash function for mapping extension to a cell (Each cell presents the
first letter of the extension file).
inside each cell there would be a list of extensions starting with the same letter.
for each node in the list there would be a red black tree for searching the filename and then
after we found the filename the program will retrieve the path of the file stored in the tree
node.
Oh by the way usually I program in c (low level) or in c++.
I think you are making a way too elaborate and complicated scheme. If locating a MyFileTree based on extension is what you want then just use SortedDictionary<string, MyFileTree> where string is your extension and you'll get a O(log n) retrieval mechanism out of the box.