i m writing a program such that it requires no of nodes to be control by some variable.
is there any way by which we can draw nodes dynamically if no, of nodes is not decided while writing a code?
Write your program in such a way that it accepts a parameter and tell graphviz to create as many nodes as the parameter says.
Related
Is there an option in CPLEX that allows the addition of cuts only at the root?
I would expect, yes, but I can't find the name of the option.
There are several ways:
set the node limit to 1 (or 0?) so that CPLEX only work on root node. You can add your cuts, then you relax the node limit, then solve it.
When you try to add a cut, do a query first to find out the node count or something like that using the query callback. Only add when the node count is 0 (or 1?)
Drop all the integer constraints and turn it into a LP. Then add your cuts, then add the integral constraints back on and solve it.
I am trying to write a compiler/code editor.
To speed up the process I want a red and black tree that returns a node which I can then use to get the strings under it, and it's position value, and use it's parent node as a place to store a token (such as alphanumeric_word or left_parenthesis).
I am having trouble finding the best way to go about this.
I basically want something that can do the following:
tree.insert("01234567890123456789",0);
node = tree.at(10);
tree.insert("string",5);
node.index(); //should be 10+length("string")
node.value(); //should be '0'
node.tokenPtr.value; //should point to a token with the value of NUMBER
I am looking for the simplest implementation of such a tree that I could modify since these can be frustrating to build and debug from scratch.
The following code is sort of what I am looking for (it has parent nodes), but it lacks an indexing feature for index look up. This is needed because I want to create a map that uses the node as it's key and node.index() as it's sorting value so that I don't have to update the keys in that map.
[[archive.gamedev.net/archive/reference/programming/features/TStorage/page2.html]]
I have tried to look at sgi's rope implimentation, but the code is overwhelming and difficult to understand.
This tutorial seems to be helpfull, however it also doesn't provide a doubly linked tree which I think can be used to find the index of a node:
[[eternallyconfuzzled.com/tuts/datastructures/jsw_tut_rbtree.aspx]]
Update:
I have found an implementation that has a parent node, however it still lacks an index count property:
[[web.mit.edu/~emin/Desktop/ref_to_emin/www.old/source_code/red_black_tree/index.html]]
I have found one solution and another that might work.
You have to use the sgi stl rope mutable_begin()+(index) iterator.
There is also this function, however I am still having trouble analyzing the sgi rope code to see what it does:
mutable_reference_at(index)
Introduction: write a program to do text prediction suggestion (like Google does when you start typing a search term). That is, as the user
types, the program will show a list of N words that the user might be in the process of typing.
enter image description here
Requirements: read in a file with words and build an internal representation
Part 1: The internal representation that you are to use is a tree with a branching factor of 26, one branch for each possible letter. Each node should also signify if ending in that node represents a word.
Example: For instance, given the string ”parrot”, following a path from the
root should end in a node that signifies that a word has occurred. Following a path for the string ”subantiq” should arrive at a node that signifies that a word does not end at that
node.
Confusion: I do not know how to create the tree in order to fill it with words from a list. Also, there is no constraint on the language.
My question are:
1. Which language would be best for implementing this?
2. how do I create the tree that will read in a list of words, in the desired structure? Pseudo code in the best language?
You can use Trie data structure for this with a branching factor of 26.r
Now to answer your questions.
Which language would be best for implementing.
ans: You can implement it either in python or in C++.
2.How do I create the tree that will read in a list of words in the desired structure.
ans: You can take reference from this.
Additionally you can take reference for pseudo code from here.
I am using neo4j-core gem (Neo4j::Node API). It is the only MRI-compatible Ruby binding of neo4j that I could find, and hence is valuable, but its documentation is a crap (it has missing links, lots of typographical errors, and is difficult to comprehend). In the Label and Index Support section of the first link, it says:
Create a node with an [sic] label person and one property
Neo4j::Node.create({name: 'kalle'}, :person)
Add index on a label
person = Label.create(:person)
person.create_index(:name)
drop index
person.drop_index(:name)
(whose second code line I believe is a typographical error of the following)
person = Node4j::Label.create(:person)
What is a label, is it the name of a database table, or is it an attribute peculiar to a node?
If it is the name of a node, I don't under the fact that (according to the API in the second link) the method Neo4j::Node.create and Neo4j::Node#add_label can take multiple arguments for the label. What does it mean to have multiple labels on a node?
Furthermore, If I repeat the create command with the same label argument, it creates a different node object each time. What does it mean to have multiple nodes with the same name? Isn't a label something to identify a node?
What is index? How are labels and indices different?
Labels are a way of grouping nodes. You can give the label to many nodes or just one node. Think of it as a collection of nodes that are grouped together. They allow you to assign indexes and other constraints.
An index allows quick lookup of nodes or edges without having to traverse the entire graph to find them. Think of it as a table of direct pointers to the particular nodes/edges indexed.
As I read what you pasted from the docs (and without, admittedly, knowing the slightest thing about neo4j):
It's a graph database, where every piece of data is a node with a certain amount of properties.
Each node can have a label (or more, presumably?). Think of it as a type -- or perhaps more appropriately, in Ruby parlance, a Module.
It's a database, so nodes can be part of an index for quicker access. So can subsets of nodes, and therefor nodes with a certain label.
Put another way: Think of the label as the table in a DB. Nodes as DB rows, which can belong to one or more labels/tables, or no label/table at all for that matter. And indexes as DB indexes on sets of rows.
Update:
I found more of an example of what I'm trying to pull off: Managing Hierarchical Data in MySQL. I want to do that but in JavaScript because I am building an app that takes in comments that are in a hierarchical structure, to be more specific reddit.com. If you have the Pretty JSON extension on your chrome web browser go to reddit and click on a threads comments and then add .json to the url to see what I am parsing.
I get the JSON data just fine, its just parsing through the comments and adding the appropriate HTML to show that its nested.
Ideas for solutions?
OLD question:
I am working on a program and I have come to a part that I need to figure out the logic before I write the code.
I am taking in data that is in a tree format but with the possibility of several children for each parent node and the only tree's I can seem to find data on are tree's with weights or tree's where at most each node has two child nodes. So I'm trying to figure out the algorithm to evaluate each node of a tree like this:
startingParent[15] // [# of children]
child1[0]
child2[5]
child2ch1[4]
...
child2ch5[7]
child3[32]
...
child15[4]
Now when I try to write out how my algorithm would work I end up writing nested for/while loops but I end up writing a loop for each level of the height of the tree which for dynamic data and tree's of unknown height with unknown number of children per node this doesn't work. I know that at some point I learned how to traverse a tree like this but its completely escaping me right now. Anyone know how this is done in terms of loops?
If you're not going to use recursion, you need an auxiliary data structure. A queue will give you a breadth-first traversal, whereas a stack will give you a depth-first traversal. Either way it looks roughly like this:
structure <- new stack (or queue)
push root onto structure
while structure is not empty
node <- pop top off of structure
visit(node)
for each child of node
push child onto structure
loop
Wikipedia References
Queue
Stack
Use recursion, not loops.
Breadth first search
Depth first search
Those should help you get started with what you're trying to accomplish
Just use recursion like
def travel(node):
for child in node.childs:
# Do something
travel(child)
The simplest code for most tree traversal is usually recursive. For a multiway tree like yours, it's usually easiest to have a loop that looks at each pointer to a child, and calls itself with that node as the argument, for all the child nodes.