JHV User's Guide

Spreadsheet

Spreadsheet in JHV is designed to display the raw data of an image or a vdata table. A spreadsheet generally displays data that can be defined in terms of three variables: two independent variables which correspond to the row and column labels, and a dependent variable, which has a value at every point in the array. There are two types of spreadsheet in JHV, image spreadsheet and vdata spreadsheet. An image spreadsheet is created from an image which represents an HDF raster image or SDS data array, and supports some image processing. A vdata spreadsheet is a table which displays a vdata and support data processing.


1. Image Spreadsheet

JHV provides the capability of creating a spreadsheet from an image. Selecting a subset area from an image in the Image Window , and clicking the spreadsheet button, you will get an spreadsheet containing the raw data of the selected image area. The image spreadsheet looks like,

The current image spreadsheet only supports "Make Image" action. The "Make Image" action makes an image from the spreadsheet. There are two options of making an image from spreadsheet, expansion factor and interpolation.

2. Vdata Spreadsheet

As described in section HDF Data Objects , an vdata object is a table in which each row has the same structure and each column contains data of the same data type. A column can be any of data types such as character, integer, float point or an array of these types. Therefore, a cell in a vdata table can be an array. If a column type is an array, only the first three elements of the array is displayed in its cell. The following is an example of such spreadsheet.

The current JHV only supports "plot" action in Vdata Spreadsheet. Clicking a column with numeric data type brings up a plot with the column values plotted against with row index numbers. Clicking another column adds that column into the plot. A vdata spreadsheet does not take any action on columns with arrays and characters. The following is an example of vdata plot with two columns (Integer and Float) plotted against the row index.

Vdata plot provides three options, plot mode, zooming, and plot style.


NCSA
The National Center for Supercomputing Applications

University of Illinois at Urbana-Champaign

hdfhelp@ncsa.uiuc.edu