1
vote
2answers
102 views

How to create a list with subscript?

I have to calculate: How can I create such a collection? Do I have to set it manually(one by one) like G1=1, H1=1, G2=2,H2=.....? UPDATE: Addtional Questions: How can I store te results into ...
13
votes
2answers
355 views

Efficient priority queues?

I'm trying to figure out how to transfer the concept of a priority queue to the functional world. Searches have turned up some implementations that use Append and other expense list copying ...
3
votes
1answer
147 views

How to determine cluster membership using FindClusters?

I have a 1000 by 3 data matrix in which for each person we have 3 scores. I want to cluster those persons into 8 cluster using Agglomerative method. I did the clusetring by: ...
10
votes
1answer
192 views

Is there a method to enumerate the keys/values of System`Utilities`HashTable

Lacking from the simple API of System`Utilities`HashTable is a method to enumerate the keys/values. ...
5
votes
1answer
165 views

What is the fastest way to maintain a large set of expressions?

In my algorithm I need to maintain a set (an unordered list of distinct elements) of expressions supporting two operations: Test an expression for membership in the set Adding a new expression to ...
1
vote
0answers
215 views

Data structure for a list of actions

The idea: I need to generate a sequence of events then run a "propagator" over the list of events where the "propagator" will update the state of the following event. I can then write functions that ...
1
vote
1answer
435 views

pointer like operations in mathematica and evaluation control

I would like to create a data structure of the type "header[pointer]" where pointer would point to a list. I will shown on an example how I'd like this to work, and where the problems are. ...
20
votes
4answers
655 views

Efficient circular buffer?

I wish to create an efficient circular buffer. That is, I wish to keep a fixed length list while appending a new value and dropping the oldest, repeatedly. As we know lists in Mathematica are ...
6
votes
1answer
224 views

Return a Part by Reference? (For accessing hierarchical / structured data)

Is there a way to return a part of a list by reference, for reading and writing? I want to do this so I can easily manipulate "rule-styled structured", i.e., hierarchical data that is loaded from a ...
13
votes
2answers
538 views

Question about designing a particular data structure

Background: I store polygons with a color assigned at the face level. In some occasions I want to use vertex colors but I want to store data efficiently, i.e. don't want to duplicate data to the ...
7
votes
1answer
292 views

Is it possible to construct a function to make a poor man's Mathematica database?

I have a function that is set up to write to a database with 10-20 standard variables with 10 fields each, but the application is going to a place where database access is not available. Can ...
8
votes
2answers
216 views

Cases[data,Colon[key,_]] vs. Cases[data,key:_] toward XPath, XQuery

Exploring methods to index and search tree-structured key:value pairs via named-entity index (key paths) as opposed to Position-based indexing. Using Rule as ...
38
votes
2answers
2k views

What is a Mathematica packed array?

A simple sounding question with a few sub questions: What is the difference between unpacked vs packed array? Are packed arrays more space efficent, how much so? Are packed arrays more time ...
65
votes
7answers
6k views

Struct equivalent in Mathematica?

I really miss having something like a struct in Mathematica. I know of (and regularly use) a couple of programming techniques which feel like a ...