GETTING STARTED USING LINKWINDS DATA LINKING The key to using LinkWinds is data linking. It provides the user the ability to interactively link the many applications of LinkWinds for concerted actions in examining data. It is especially effective in detecting trends, anomalies and correlations. Data linking is affected through two icons. The link icon is a button displaying two interlocked rings, while the unlink icon displays two rings that are separated. LinkWinds' objects may have a single link button, in the case of the DataObject; the full set of link and unlink buttons, the case for all controls such as the slider; or no buttons, in the case of a display object. To perform a link, the left-mouse button is pressed while the cursor is placed on the appropriate button, and a "rubber band" is dragged out and dropped into the application to be linked. To break the link, the same thing is done using the unlink button. The rubber bands indicating the current links may be displayed at any time during a session by placing the cursor in the logo of the top-level menu and pressing the left-mouse button. They are shown emanating from the source button to the center of the destination object. There are two simple rules to follow in applying the linking paradigm: 1. When, as a result of a top-level menu selection of a control or display, an empty window appears on the screen, put data into it. This is done by linking a DataObject into the window. 2. When an object with the pair of link symbols appears, exercise its control function by linking it into the object to be controlled. Once the link is made, the message flow to the object is enabled. For instance, in the case of links from a slider, each time the slider is moved, its final value is broadcast to all objects to which it is linked. When the "track" toggle is pressed, a continuous stream of messages results as the slider is moved. All LinkWinds controls are operated with the left-mouse button and all menus with the right-mouse button. A SAMPLE SESSION To help you get started using LinkWinds, a sample session is presented below. We show the steps to be taken to look one of the sample databases, and explain what is accomplished by the steps. 1. In your own LinkWinds directory, execute LinkWinds by typing lw. The LinkWinds top-level menu will appear under the cursor. Place it where you wish and press the left-mouse to fix it there. 2. Open the "Databases" menu button and under the "Ocean" entry, select the "oceanAtlas" item from the cascaded menu. This process will result in the activation of the next, or "Data" menu button. 3. Open the "Data" menu and you will see the files associated with the selected database. In this case, there are three: "Oxygen Content", "Temperature" and "Salinity". Select "Oxygen Content" and a DataObject representing that data set will appear at the cursor to be placed where desired. Then, in like manner, bring up the "Temperature" data set. 4. Open the "Tools" menu button and bring "Image" to the screen. You'll observe an empty window. 5. Link the "Oxygen Content" DataObject to the Image window. The data and metadata will become accessible to Image and the data will be rendered. 6. Open the "Tools" menu again and bring a second Image to the screen. 7. Link the "Temperature data" into this Image. 8. Bring up a Slider from the "Tools" menu and link it to each of the Image objects. By moving the slider you can then explore the two data sets simultaneously at the various ocean depths. If you press the "Track" button, the changes in depth will occur continuously as the slider is moved. 9. Bring up the 2D ScatterPlot. Link to it the "Oxygen Content" DataObject, and the "Temperature" DataObject, in that order. It will display the two datasets scattered against one another. At a depth of 0 (on the Slider) you can observe a very high degree of anticorrelation: as we expect, the higher the water temperature, the less oxygen will be dissolved in it. 10. Link the Slider to the 2D ScatterPlot and you can look at the data correlations as a function of ocean depth. 11. Move the slider to a depth of 100 meters. At this depth, you can observe a region of low oxygen off the west coast of Central America. 12. Select "Resize Bound Box" from the "Bound Box" cascade menu in Image1. The cursor, when placed over the oxygen content image, will display an upper left-hand corner symbol. Place this somewhere in the upper left vicinity of the low oxygen region and press the left mouse button. While holding it down, drag a bounding box to the lower right vicinity of that region. Release the mouse button and you've defined a bounding box. 13. Link Image1 into the 2D ScatterPlot. You will see that now the only data scattered is that lying within the bounding box. You can redraw the box at will, or by selecting the menu item, "Move Bound Box" from the "Bound Box" cascade menu, you can move an existing box around the image to look at correlations in other regions. Statistical information about the correlations is displayed in a text window at the bottom of the 2D ScatterPlot. This completes your sample session which demonstrates many of the LinkWinds operations, and its approach to data display and exploration. Other links may be tried at will. Linking is designed to be learned through trial and error. If an application doesn't understand the message received through a link, it will ignore it. For details in the use of each application, help windows can be brought up by pressing the button contain "?". At top level help menu is available under the LinkWinds' "System" menu item. You have just gone through the steps that we used to create the sample macro "Startup", which you can find under the "macros" menu button. If you want to exercise this macro, open the "macros" menu button, and under the "Run Macro" item select "Startup". All of the steps you have just taken will be repeated automatically. The steps for creating a macro are given in Section 12. Another way to execute this sequence of steps is to start LinkWinds with the -r switch and the .lynx filename. lw -r startup.lynx This demonstrates the LinkWinds rerun mode which can be used to setup an initial environment. For further instructions, see the LinkWinds User's Guide and Reference Manual.