Graph Tool

Introduction

Once a Query which returns data has been executed it is possible to access the information retrieved as a graph. To use this facility click the Graph icon  in the Toolbar and then left click on the site whose data you wish to graph.

By default, the data are graphed against one of three parameters depending on the data returned from the query:

• Any data that is part of a time series will be plotted against date/time.
• Any data that has depth, but no period statistics calculated, will be plotted against depth (on the y-axis).

Once the graphing tool is loaded the axes may be changed and other data may be loaded.

The menu bar in the Graph Tool window contains the following options:

• File - Print/Exit
• Properties - Change the properties of the graph, e.g. line/symbols, axes etc
• Zoom - Zoom in or out
• Attributes on Y - Turn attributes on/off on the Y-axis
• Plot Versus - Change what the data is plotted against
• Statistics - Change the statistics displayed
• Sites - Add sites to a graph
• Threshold - Add a threshold to an image
• Transect - display multiple or single transects

File

The File menu contains the following options:

• Print - Print the contents of the Graph Tool window
• Exit - Exit Graph Tool window

Select a printer and change the printer properties in the standard Windows manner.

Zoom Menu

The Zoom menu items provide a comprehensive means of altering the scale at which the graph is viewed. This is useful when details of a complicated graph or a graph with attributes covering different temporal limits are being viewed. An example of the use of the Zoom tools is shown below. The second image shows the effect of zooming in on the area highlighted by the yellow square in the first image. Selecting Zoom to full extent of data will restore the graph to its original scale.

Full scale:

Zoomed in:

Properties

The Properties menu contains the following options:

• Symbols only - display data in the Graph Tool window using symbols only
• Lines only - display data in the Graph Tool window using lines only
• Symbols and lines - display data in the Graph Tool window using both symbols and lines
• Bar Charts - display data in the Graph Tool window using bar charts
• Axes - change the extent of axes and the number of ticks required
• Grid lines - add/remove grid lines from the graph
• Log scale for Attributes - change the axes to log scales (with the exception of date/time axes)
• Threshold - set a threshold value for the graph
  

Axes

By default, the axes match the range of data to be graphed. They may also be set manually by selecting Axes from the Properties Menu.

Threshold

An absolute threshold value or a threshold range may be set for the selected attribute. This may be useful for visualizing how often a limit (e.g. statutory) has been exceeded. This option sets the value but does not display it on the graph. To display the threshold value use the User defined option on the Threshold menu.

Attributes on Y

The Attributes on Y menu contains the following option:

• Choose attribute(s)  - choose from the attributes listed which are to be plotted on the Y axis

Initially, all attributes within a query are displayed together on a graph. If you wish to turn some of the attributes off you can do so by unchecking the menu item in the 'Attributes On Y' Menu.

Plot Versus

The Plot Versus menu contains the following options:

• Time - toggles the plotting of attributes against time
• Depth - plots data versus depth
• Select Attribute(s) - plots data versus other attributes retrieved in the same layers
• Attributes on Y - toggles whether the attributes are plotted to the Y axis or the X axis

For data retrieved with both time and depth it is possible to change the value against which the data are plotted. To create a depth profile, select Depth from the Plot Versus menu and then plot the attributes on the X-axis by unchecking the Attributes on Y menu item from the Plot Versus menu.

It is also possible to plot one attribute against another by selecting an attribute from the Plot Versus menu. It is important to note that when an attribute is selected from the Plot Versus menu then it is automatically deselected from the Attributes On Y menu, to avoid plotting that data as a straight line on the graph. Therefore, when you return to plot the data against time or depth you will need to turn the attribute back on in the Attributes On Y menu.

When plotting one attribute against another, only coincident data are shown.   The data must coincident in terms of time and depth.

Statistics

The Statistics menu contains the following options:

• Full data set - displays data in the Graph Tool window using the full data set (default)
• Mean - displays data in the Graph Tool window using mean values
• Min - displays data in the Graph Tool window using minimum values
• Max - displays data in the Graph Tool window using maximum values
• Mean + Min/Max - displays data in the Graph Tool window using mean, minimum and maximum values
• Mean + Std Dev - displays data in the Graph Tool window using mean and standard deviation values

By default, the full dataset is displayed in a graph. To display the statistics that were calculated during the query, select Statistics from the Menu Bar and chose the statistic required.

Statistics:

Note: When you select a statistics plot you should note that some restrictions from the map display still apply. For example, if you have retrieved depth and time with your data and then plot a time series, the time series shown will relate only to the currently displayed depth interval (shown in the status bar). Conversely, a depth profile of statistics will only show data from the current time.

Sites

The Sites menu contains the following options:

• Add Sites to graph - selects and displays data for up to 4 additional sites in the Graph Tool window
• Select site(s) to display - displays data for the selected sites in the Graph Tool window

To compare data between sites, it is possible to add up to 5 sites by selecting 'Add Sites to Graph' from the Sites Menu. Each site is represented by a different shaped symbol and/or different dashed lines. The colour of each symbol and line remains true to the attribute colour on the map display (Example).

Threshold

The Threshold menu contains the following options:

• Consent from database (not currently implemented)
• User specified - add/remove threshold value from the graph

The User specified option acts as a toggle to add or remove from the graph a horizontal bar representing the threshold vale set with the Threshold option of the Properties menu.

Transect

The Transect menu contains the following options:

• Show current time and height - shows transect for the current date and depth as determined on the Time/Depth Bar of the Map Window.
• Select Specific Transect - select a transect from the times available.
• Show all dates - show transects for all time slices.
• Show all heights - show transects for all depth slices.

To show transects for all dates or depths, or to show the transect for the current time and depth use the above options from the Transect menu. To add transects for selected dates use Select Specific Transect and the following list will appear.

Select the transects you wish to display and click OK.

When you are graphing vector data with depth slices it is possible to graph the attribute values along a vertical transect. The following graph has been produces after drawing a transect on such data and then selecting Plot Versus->Height/Depth and Transect->Show all heights.

Other Notes

Some attributes can be defined as character/string rather than numerical data. When data of this type are plotted on a graph a section of the graph area is reserved for the character data. For time series data this will be the top part of the graph and for depth plots will be the right hand section. The colour of the symbol relates to the colours specified in the map legend.

Notes: The generic nature of the graphing tool means that it is possible to create some unusual effects, therefore be sure that you have chosen appropriate parameters.