Created cookbook for passing vectors/matrix to features object

doc/cookbook/source/examples/getting_started/features.rst

@@ -0,0 +1,60 @@
+=======================
+Passing data to Shogun
+=======================
+
+In this getting started guide, we will look at how to pass data random data to a matrix & pass it through a features object . We will create a matrix as shown :
+
++-------------+-------------+-----------+-----------+
+|  	      |  Sample 1   |  Sample 2 |  Sample 3 |
+|   	      |             |           |           |
++=============+=============+===========+===========+
+| Feature 1   | 1	    | 2	        | 3	    |
++-------------+-------------+-----------+-----------+
+| Feature 2   | 4           | 5         | 6         |
++-------------+-------------+-----------+-----------+
+
+Then, we extract features for example 1 (values 1 and 4)
+
+
+-------
+Example
+-------
+
+We start off by creating a real matrix and inserting values 1 through 6. 
+
+.. sgexample:: features.sg:create_matrix
+
+Now we can pass the data from the matrix to the features object.
+
+.. sgexample:: features.sg:create_features
+
+We've got a features object containg our data , so we can now extract the features
+for Sample 1.
+
+.. sgexample:: features.sg:get_features
+
+This vector now contains values 1 and 4.
+
+----
+NOTE
+----
+
+It is important to note that conventionally, data is stored in a row-major fashion,
+meaning two row vector of size 3.
+However, in Shogun, this will be column vectors of dimension 2. 
+
+Note that data is stored in column major format, i.e. each column of the matrix corresponds to
+an observation / feature vector, where each vector consists of a number of variables that is equal
+to the number of rows of the matrix.
+
+Also, it is essential to map the data types of the features object & vector i.e one cannot pass
+a vector of integers to a method that expects floats. 
+Note that features are type-safe, e.g. you can only pass 64 bit floating point numbers to :sgclass:`RealFeatures` .
+
+----------
+References
+----------
+:wiki:`Feature (machine learning)`
+
+:wiki:`Row- and column-major order`
+

doc/cookbook/source/index.rst

@@ -16,6 +16,16 @@ Quickstart
 
    quickstart/interfaces
 
+Getting Started
+---------------
+
+.. toctree::
+   :maxdepth: 1
+   :glob:
+   :caption: Getting started
+
+   examples/getting_started/**
+
 Binary classifier
 -----------------
 

examples/meta/src/getting_started/features.sg

@@ -0,0 +1,18 @@
+
+#![create_matrix]
+RealMatrix real_matrix(2,3)
+real_matrix[0,0]= 1
+real_matrix[0,1]= 2
+real_matrix[0,2]= 3
+real_matrix[1,0]= 4
+real_matrix[1,1]= 5
+real_matrix[1,2]= 6
+#![create_matrix]
+
+#![create_features]
+RealFeatures features(real_matrix)
+#![create_features]
+
+#![get_features]
+features.get_feature_vector(0)
+#![get_features]