Package opendap.dap

Class DGrid

  • All Implemented Interfaces:
    Serializable, Cloneable, ClientIO
    public class DGrid
extends DConstructor
implements ClientIO
    This class holds a DArray and a set of "Map" vectors. The Map vectors are one-dimensional arrays corresponding to each dimension of the central Array. Using this scheme, a Grid can represent, in a rectilinear array, data which is not in reality rectilinear. An example will help make this clear.

    Assume that the following array contains measurements of some real quantity, conducted at nine different points in space: 

     A = [ 1  2  3  4 ]
     [ 2  4  6  8 ]
     [ 3  6  9  12]

    To locate this Array in the real world, we could note the location of one corner of the grid, and the grid spacing. This would allow us to calculate the location of any of the other points of the Array.

    This approach will not work, however, unless the grid spacing is precisely regular. If the distance between Row 1 and Row 2 is not the same as the distance between Row 2 and Row 3, the scheme will break down. The solution is to equip the Array with two Map vectors that define the location of each row or column of the array: 

           A = [ 1  2  3  4 ] Row = [ 0 ]
           [ 2  4  6  8 ]       [ 3 ]
           [ 3  6  9  12]       [ 8 ]
 
    
  Column = [ 0  2  8  27]

    The real location of the point in the first row and column of the array is now exactly fixed at (0,0), and the point in the last row and last column is at (8,27).

    See Also:
    BaseType, DArray, Serialized Form

    • Field Detail

      • arrayVar

        protected DArray arrayVar
        The Array component of this DGrid.

      • mapVars

        protected Vector mapVars
        The Map component of this DGrid.

    • Constructor Detail

      • DGrid

        public DGrid()
        Constructs a new DGrid.

      • DGrid

        public DGrid​(String n)
        Constructs a new DGrid with name n.
        Parameters:
        n - the name of the variable.

    • Method Detail

      • getTypeName

        public String getTypeName()
        Returns the OPeNDAP type name of the class instance as a String.
        Specified by:
        getTypeName in class BaseType
        Returns:
        the OPeNDAP type name of the class instance as a String.

      • elementCount

        public int elementCount​(boolean leaves)
        Returns the number of variables contained in this object. For simple and vector type variables, it always returns 1. To count the number of simple-type variable in the variable tree rooted at this variable, set leaves to true.
        Overrides:
        elementCount in class BaseType
        Parameters:
        leaves - If true, count all the simple types in the `tree' of variables rooted at this variable.
        Returns:
        the number of contained variables.

      • addVariable

        public void addVariable​(BaseType v,
                        int part)
        Adds a variable to the container.
        Specified by:
        addVariable in class DConstructor
        Parameters:
        v - the variable to add.
        part - the part of the DGrid to be modified. Allowed values are ARRAY or MAPS.
        Throws:
        IllegalArgumentException - if an invalid part was given.

      • getVar

        public BaseType getVar​(int index)
                throws NoSuchVariableException
        Gets the indexed variable. For a DGrid the index 0 returns the DArray and indexes 1 and higher return the associated map Vectors.
        Specified by:
        getVar in class DConstructor
        Parameters:
        index - the index of the variable in the Vector Vars.
        Returns:
        the indexed variable.
        Throws:
        NoSuchVariableException - if the named variable does not exist in this container.

      • getVarCount

        public int getVarCount()
        Get the number of contained variables (for use with getVar()
        Specified by:
        getVarCount in class DConstructor
        Returns:
        the number of contained variables

      • getVariables

        public Enumeration getVariables()
        Return an Enumeration that can be used to iterate over the members of a Structure. This implementation provides access to the elements of the Structure. Each Object returned by the Enumeration can be cast to a BaseType.
        Specified by:
        getVariables in class DConstructor
        Returns:
        An Enumeration

      • checkSemantics

        public void checkSemantics​(boolean all)
                    throws BadSemanticsException
        Checks for internal consistency. For DGrid, verify that the map variables have unique names and match the number of dimensions of the array variable.
        Overrides:
        checkSemantics in class BaseType
        Parameters:
        all - for complex constructor types, this flag indicates whether to check the semantics of the member variables, too.
        Throws:
        BadSemanticsException - if semantics are bad, explains why.
        See Also:
        BaseType.checkSemantics(boolean)

      • printDecl

        public void printDecl​(PrintWriter os,
                      String space,
                      boolean print_semi,
                      boolean constrained)
        Write the variable's declaration in a C-style syntax. This function is used to create textual representation of the Data Descriptor Structure (DDS). See The OPeNDAP User Manual for information about this structure.
        Overrides:
        printDecl in class BaseType
        Parameters:
        os - The PrintWriter on which to print the declaration.
        space - Each line of the declaration will begin with the characters in this string. Usually used for leading spaces.
        print_semi - a boolean value indicating whether to print a semicolon at the end of the declaration.
        constrained - a boolean value indicating whether to print the declartion dependent on the projection information. This is only used by Server side code.
        See Also:
        BaseType.printDecl(PrintWriter, String, boolean)

      • printVal

        public void printVal​(PrintWriter os,
                     String space,
                     boolean print_decl_p)
        Prints the value of the variable, with its declaration. This function is primarily intended for debugging OPeNDAP applications and text-based clients such as geturl.
        Specified by:
        printVal in class BaseType
        Parameters:
        os - the PrintWriter on which to print the value.
        space - this value is passed to the printDecl method, and controls the leading spaces of the output.
        print_decl_p - a boolean value controlling whether the variable declaration is printed as well as the value.
        See Also:
        BaseType.printVal(PrintWriter, String, boolean)

      • externalize

        public void externalize​(DataOutputStream sink)
                 throws IOException
        Writes data to a DataOutputStream. This method is used primarily by GUI clients which need to download OPeNDAP data, manipulate it, and then re-save it as a binary file.
        Specified by:
        externalize in interface ClientIO
        Parameters:
        sink - a DataOutputStream to write to.
        Throws:
        IOException - thrown on any OutputStream exception.

      • printXML

        public void printXML​(PrintWriter pw,
                     String pad,
                     boolean constrained)
        Overrides:
        printXML in class DConstructor
        Parameters:
        pw - Where to print
        pad - Padding for iondentation (makes the output easier for humans to read).
        constrained - If true then only projected variables (and their Attributes) will be printed.

      • getArray

        public DArray getArray()

      • projectedComponents

        public int projectedComponents​(boolean constrained)
        How many prohected components of this Grid object?
        Returns:
        The number of projected components.

      • projectionYieldsGrid

        public boolean projectionYieldsGrid​(boolean constrained)
        When projected (using whatever the current constraint provides in the way of a projection) am I still a Grid?
        Returns:
        True if projected grid is still a grid. False otherwise.