Difference between revisions of "MdTable"

(Copy/pasted from user guide)
(adorned with links, italics)
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Returns a multi-dimensional array from a two-dimensional table
 
Returns a multi-dimensional array from a two-dimensional table
 
of values. T is a two-dimensional array (i.e., a table) indexed by
 
of values. T is a two-dimensional array (i.e., a table) indexed by
−
Rows and Cols. Each row of T specifies the coordinates of a cell
+
''Rows'' and ''Cols''. Each row of ''T'' specifies the coordinates of a cell
 
in a multi-dimensional array, along with the value for that cell.
 
in a multi-dimensional array, along with the value for that cell.
  
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If Vars is omitted, the dimensions of the final result are specified
 
If Vars is omitted, the dimensions of the final result are specified
−
by the first n-1 elements of Cols (n=size(Cols)). In this case, the
+
by the first ''n-1'' elements of ''Cols'' (''n=size(Cols)''). In this case, the
 
elements of Cols must be index identifiers or index names.
 
elements of Cols must be index identifiers or index names.
  
−
The first n-1 columns of T specify the coordinates of a cell in the
+
The first ''n-1'' columns of ''T'' specify the coordinates of a cell in the
−
result. The final column of T specifies the value for the indicated
+
result. The final column of ''T'' specifies the value for the indicated
 
cell.
 
cell.
  
−
Before using MDTable, you must define all of the indexes for the
+
Before using ''MDTable'', you must define all of the indexes for the
 
result. Each index must include all values that occur in the corresponding
 
result. Each index must include all values that occur in the corresponding
−
column of T or an error will result. The Unique() function
+
column of ''T'' or an error will result. The [[Unique]]() function
 
is useful for defining the necessary indexes.
 
is useful for defining the necessary indexes.
  
−
It is possible that two or more rows of T specify identical coordinates.
+
It is possible that two or more rows of ''T'' specify identical coordinates.
 
In this case, a conglomeration function is used combine
 
In this case, a conglomeration function is used combine
 
the values for the given cell. The conglomFn parameter is a text
 
the values for the given cell. The conglomFn parameter is a text
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Possible values are: "sum" (default), "min", "max", "average", or
 
Possible values are: "sum" (default), "min", "max", "average", or
 
"product".
 
"product".
 +
 +
(new to 4.0 -- to fill in): Using your own UDF-defined conglomeration functions.
  
 
It is also possible that no row in T corresponds to a particular cell.
 
It is also possible that no row in T corresponds to a particular cell.
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= Example =
 
= Example =
  
−
Suppose T, Rows, and Cols are defined as indicated by the following
+
Suppose ''T'', ''Rows'', and ''Cols'' are defined as indicated by the following
 
table:
 
table:
  
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|}
 
|}
  
−
  MDTable(T,Rows,Cols,[Car_type,Mpg],average’,’n/a’) -->
+
  MDTable(T,Rows,Cols,[Car_type,Mpg],'average','n/a') -->
  
 
{| border="1"
 
{| border="1"
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Notice that in the example, Rows 6 and 7 both specified values
 
Notice that in the example, Rows 6 and 7 both specified values
−
for Car_type=BMW, Mpg=35. The ‘average’ conglomeration function
+
for ''Car_type=BMW, Mpg=35''. The "average" conglomeration function
 
was used to combine these.
 
was used to combine these.
 +
 +
= See Also =
 +
 +
* [[Unique]]
 +
* [[MdArrayToTable]]

Revision as of 22:50, 2 February 2007


MdTable(T,Rows,Cols,Vars,conglomFn,missingval)

Returns a multi-dimensional array from a two-dimensional table of values. T is a two-dimensional array (i.e., a table) indexed by Rows and Cols. Each row of T specifies the coordinates of a cell in a multi-dimensional array, along with the value for that cell.


The dimensions of the final result are given by the optional parameter Vars. Vars must be a list of index identifiers or index names. The length of Cols must be one greater than the length of Vars.

If Vars is omitted, the dimensions of the final result are specified by the first n-1 elements of Cols (n=size(Cols)). In this case, the elements of Cols must be index identifiers or index names.

The first n-1 columns of T specify the coordinates of a cell in the result. The final column of T specifies the value for the indicated cell.

Before using MDTable, you must define all of the indexes for the result. Each index must include all values that occur in the corresponding column of T or an error will result. The Unique() function is useful for defining the necessary indexes.

It is possible that two or more rows of T specify identical coordinates. In this case, a conglomeration function is used combine the values for the given cell. The conglomFn parameter is a text value specifying which conglomeration function is to be used. Possible values are: "sum" (default), "min", "max", "average", or "product".

(new to 4.0 -- to fill in): Using your own UDF-defined conglomeration functions.

It is also possible that no row in T corresponds to a particular cell. In this case, the cell value is set to missingval, or if the missingval parameter is omitted, the cell value is set to undefined. Undefined values can be detected using the IsUndef() function.

Library

Array

Example

Suppose T, Rows, and Cols are defined as indicated by the following table:

Rows v, Cols >>
Car_type Mpg X
1 VW 26 2185
2 VW 30 1705
3 Honda 26 2330
4 Honda 35 2210
5 BMW 30 2955
6 BMW 35 2800
7 BMW 35 2870 
MDTable(T,Rows,Cols,[Car_type,Mpg],'average','n/a') -->
Rows v, Cols >>
Car_type Mpg X
VW 2185 1705 n/a
Honda 2330 n/a 2210
BMW n/a 2955 2835

Notice that in the example, Rows 6 and 7 both specified values for Car_type=BMW, Mpg=35. The "average" conglomeration function was used to combine these.

See Also

Comments


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