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Chapter 7 ....continued
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The Cursor function button is used to obtain discrete values from data plots appearing in the display window. When pressed, a vertical cursor appears in the active plot frame which can then be positioned to yield discrete data values in the data plot. This function can also be driven by manually typing in an x value in the selection area ; the program then responds by providing the corresponding y axis values for all data plots in the active plot frame.
7.4.11
The Cursor button
Example 16 The user wants to obtain the precise y values of three data sets plotted on a common x axis.
Display three data sets in a single plot frame in the display window Press the Cursor button in the menu window A white vertical bar appears in the display window in the active plot frame. The mouse cursor changes to a two-way horizontal arrow to indicate that the bar can be moved laterally by clicking the mouse elsewhere in the display window. The x axis position of the bar is listed in the selection area. In the upper left-hand corner of the information area is shown the corresponding y value for each data set in the active plot frame
Move the mouse cursor left or right of the bar and click The position of the bar changes and so too do the x and y values displayed in the selection area and information area
Change the position of the bar manually by making the menu window active, pressing the backspace key to delete the x axis value displayed in the selection area, typing in a new value and then pressing <Return> The bar moves to the new x axis position and the y values displayed in the information area change
The Evaluate function button is used to obtain the sum and average of y values between any two x axis values in a data plot mapped in the display window. It works in a way similar to the Cursor function button; in this case two vertical bars are placed in the active plot frame and the y values between them are interrogated by the program. Again, this function can be operated by manually typing in the upper and lower x bounds of the area of interest.
7.4.12
The Evaluate button
Example 17 The user wants to obtain the predicted mean and total transpiration between days 25 and 75 as stored in a .hyd file.
Select the .hyd file of interest and plot the "Transpiration" option Press the Evaluate function button in the menu window Two items labelled "Lower Bound : 0" and "Upper Bound : 0" appear in the selection area indicating that no range has yet been selected. The "Lower Bound:" option is highlighted
Move the mouse cursor to the display window and click anywhere in the active plot frame A white vertical bar appears in the display window in the active plot frame. The "Upper Bound :" option in the selection area is now highlighted
Move the mouse cursor back to the display window and click anywhere to the right of the bar in the active plot frame Another white vertical bar appears in the display window in the active plot frame. The two bars now define the x axis range over which the summation and averaging will be computed. In the upper left-hand corner of the information area is shown the sum and average of the y values for this range of x axis values
Move the lower bound of the area by clicking the mouse cursor near the left-hand bar The new sum and average y values appears in the information area
Change the position of the upper bound bar manually by making the menu window active, selecting the "Upper Bound :" option in the selection area, pressing the backspace key to delete the upper bound value, typing in a new value and then pressing <Return> The upper bound bar moves to the new x axis position and the y values displayed in the information area change
The Dump function button is used to capture screen images for output to a colour printer. When the button is pressed, all information in the display window is written to two files:
7.4.13
The Dump button
Dump_File an xwindows dump (xwd) format file Dump_File.ps a postscript format file
Example 18 The user wants to dump the screen image in the display window.
Press the Dump button in the menu window One beep sounds at the start of the dump, two beeps sound when the dump is finished. The image in the display window is written to files Dump_File and Dump_File.ps to files
The QUIT function button is used to terminate a session with Topog_Chart.
7.4.14
The QUIT button
7.5 |
Some hints on using Topog_Chart |
Display window screen images dumped using the Dump function button can be reviewed by using the xwud command. This is a command line operation that must be invoked outside of program Topog_Display.
7.5.1
Reviewing a dumped file
The image stored in Dump_File will be drawn in the display window. Alternatively, the file Dump_File.ps can be viewed using the common UNIX program, "Ghostscript".
To invoke the xwud command, type: $ xwud < Dump_File
If you do not want to sacrifice a process window, Topog_Chart can be run in background mode by typing:
7.5.2
Operating Topog_Chart in background mode
at the program startup stage. By doing this, you can toggle back to the parent window and execute command line functions.
To run Topog_Chart in background mode, type: $ _display &
The size, location, colour and style of the display window and menu window in Topog_Chart can be customised by modifying the .Xdefaults file. See Appendix D for further details.
7.5.3
Customising the size and appearance of your windows
| Take me out of frames | on to Chapter 8 ....... |
