The QtiPlot Handbook
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# The Data Menu

This menu is visible and active only when a graph window is selected. Commands in this menu will act on the plot/layer that is currently active in the graph window. All of these commands are switches - that is, they switch on an operational mode which remains in effect until it is canceled by selecting another command or by using the Disable tools command.

## Data -> Disable tools

For many of the remaining commands in this menu, QtiPlot will be locked into a special mode corresponding to that command, and that command's special pointer will be used instead of the normal pointer. This command is used to exit any of these special modes, returning QtiPlot to its normal mode and pointer behavior.

## Data -> Zoom In/Out and Drag Canvas

Switches the active plot layer into a dynamic zoom/drag mode. Upon command execution, the default mode is "dynamic drag". To drag the plot, simply left click anywhere in the plotting area and drag the plot around with the mouse. Drop it at the new location by releasing the left mouse button. To zoom the plot, switch to dynamic zoom mode by first right clicking somewhere in the plot area. (This will probably pop-up a context menu that you should ignore.) Next, left click at a suitable zoom reference point in the plot area to enter dynamic zoom mode (this will also dismiss any pop-up menu). Once in dynamic zoom mode, scale the plot by moving the mouse cursor up to zoom out, or down to zoom in. Right and left mouse movements have no effect. You should use some foresight in picking the zoom reference point. For example, selecting a point at the bottom of the plot area will limit zooming to upward mouse travel - that is, you will only be able to zoom out. Once a suitable zoom factor has been found, left click anywhere in the plot to accept the zoom and return to dynamic drag mode.

Note that the mouse wheel is always active when using this command. It can be used to zoom while in either dynamic drag or dynamic zoom modes. Also note that in either mode, zooming leaves the plot's aspect ratio unchanged.

## Data -> Zoom/Drag Canvas Horizontally

Switches the active plot layer into a dynamic zoom/drag mode which is limited to the horizontal direction. Upon command execution, the default mode is "dynamic horizontal drag". To drag the plot, simply left click anywhere in the plotting area and drag the plot to the right or left with the mouse. Drop it at the new location by releasing the left mouse button. Note that it may appear that you can move the plot up or down while dragging, but the original vertical location will be restored when the plot is dropped at the new horizontal location. To zoom the plot, switch to dynamic horizontal zoom mode by first right clicking somewhere in the plot area. (This will probably pop-up a context menu that you should ignore.) Next, left click at a suitable zoom reference point in the plot area to enter dynamic horizontal zoom mode (this will also dismiss any pop-up menu). Once in dynamic horizontal zoom mode, scale the plot's width by moving the mouse cursor up to zoom out, or down to zoom in. Right and left mouse movements have no effect. You should use some foresight in picking the zoom reference point. For example, selecting a point at the bottom of the plot area will limit zooming to upward mouse travel - that is, you will only be able to zoom out. Once a suitable zoom factor has been found, left click anywhere in the plot to accept the zoom and return to dynamic horizontal drag mode.

Note that the mouse wheel is always active when using this command. It can be used to zoom while in either dynamic horizontal drag or dynamic horizontal zoom modes. Also note that in either horizontal mode, zooming will change the plot's aspect ratio.

## Data -> Zoom/Drag Canvas Vertically

Switches the active plot layer into a dynamic zoom/drag mode which is limited to the vertical direction. Upon command execution, the default mode is "dynamic vertical drag". To drag the plot, simply left click anywhere in the plotting area and drag the plot up or down with the mouse. Drop it at the new location by releasing the left mouse button. Note that it may appear that you can move the plot right or left while dragging, but the original horizontal location will be restored when the plot is dropped at the new vertical location. To zoom the plot, switch to dynamic vertical zoom mode by first right clicking somewhere in the plot area. (This will probably pop-up a context menu that you should ignore.) Next, left click at a suitable zoom reference point in the plot area to enter dynamic vertical zoom mode (this will also dismiss any pop-up menu). Once in dynamic vertical zoom mode, scale the plot's height by moving the mouse cursor up to zoom out, or down to zoom in. Right and left mouse movements have no effect. You should use some foresight in picking the zoom reference point. For example, selecting a point at the bottom of the plot area will limit zooming to upward mouse travel - that is, you will only be able to zoom out. Once a suitable zoom factor has been found, left click anywhere in the plot to accept the zoom and return to dynamic vertical drag mode.

Note that the mouse wheel is always active when using this command. It can be used to zoom while in either dynamic vertical drag or dynamic vertical zoom modes. Also note that in either vertical mode, zooming will change the plot's aspect ratio.

## Data -> Zoom in (Ctrl-+)

Switches the active plot layer to zoom mode. The mouse cursor shape changes to a magnifying lens when it is inside a plot canvas. To zoom the plot, draw a box around a selected part of the plot by clicking at one corner of the desired box, dragging the mouse pointer to the opposite corner of the box and clicking a second time. The plot will be zoomed up such that the contents of the drawn box now fills the existing plotting area.

## Data -> Zoom out (Ctrl--)

This command cancels a previous zoom operation. A zoom history is kept so that you can do multiple zoom out commands to step backwards through the zoom history. A separate zoom history is maintained for each plot layer. Executing this command does not set any special mode of its own but it will cancel any other special mode that is currently in effect (i.e., it performs an implicit Disable tools command).

## Data -> Rescale To Show All (Ctrl-Shift-R)

Rescales the active plot layer after a zoom operation so that all data on the graph is visible. This command does not set any special mode of its own, but unlike the Zoom out command, it does not alter any other mode that may be in effect. Nevertheless, it does delete the zoom history of the rescaled plot.

## Data -> Data Reader (Ctrl-D)

Shows a red cross cursor and opens the Data Display toolbar giving easy and quick access to the values of the data points. Select data points by moving the cursor with the Left and Right arrow keys or, more easily and quickly, by clicking on them with the mouse. Navigate through the curves on the plot layer with the Up and Down arrow keys. The [Home] key makes the data reader jump to the beginning of the selected curve and the [End] key to its end point.

## Data -> Select Data Range (Alt-S)

Shows two vertical line cursors that are used for selecting a data range when performing analysis operations. Only one cursor is active at a time. The active cursor is red, the other is black. You change which cursor is active with the Left and Right arrow keys. Move the active cursor with the arrows keys while keeping the Ctrl key pressed or, more easily and quickly, by clicking on a curve point. Note that the mouse cursor shape changes to a rectangular target while inside the active plot canvas. Navigate through the curves on the plot layer using the Up and Down arrow keys. When this tool is active you can easily copy, paste or cut the whole selected data range using the well-known shortcuts: Ctrl+C, Ctrl+V and Ctrl+X, respectively.

## Data -> Screen Reader

Opens the Data Display toolbar and changes the mouse cursor shape to a small cross target. The coordinates of the cursor with respect to the axes of the active plot layer are displayed in a text field that floats along with the mouse cursor. Clicking the left mouse button at any point will draw a red crosshair at that point and copy the x and y coordinates of that point into the data display.

## Data -> Draw Data Points

This command is very similar to the Screen Reader command but with the addition of the ability to add data points to a plot by double clicking at each of the desired points. Each invocation of this command will create a new table titled "DrawN", where N is an integer number that is incremented after each new table addition. These tables can be renamed and reformatted after creation using the standard window manipulation commands.

## Data -> Move Data points (Ctrl-Alt-M)

Allows modification of the position of data points on the active plot layer by simple drag-and-drop. When selecting this command, you will be asked to confirm that you understand that any changes you make will automatically modify the data in the corresponding tables (as well as all plots depending on that data). The coordinates of the cursor with respect to the axes of the plot layer are displayed in a text field that floats along with the mouse cursor. However, the Data Display toolbar is also opened to provide a higher resolution display the new coordinates.

## Data -> Remove Bad Data Points (Alt-B)

Allows removal of data points from the active plot layer by double-clicking on them. When selecting this command, you will be asked to confirm that you understand that any changes you make will also modify the data in the corresponding tables (as well as all plots depending on that data). The coordinates of the cursor with respect to the axes of the plot layer are displayed in a text field that floats along with the mouse cursor. The coordinates of all points selected for removal are shown in the Data Display toolbar.

## Data -> Remove Bad Data Points

Allows dragging an entire curve on the selected plot layer. Left Click and hold down the mouse button on any point on a curve to select the curve for dragging. A red cross-hair will be drawn at the point to indicate that the curve is selected. The curve may then be dragged around on the plot layer with the mouse as long as the left mouse button is held down. Releasing the mouse button will drop the curve at the new location. This process moves all the data points and changes the coordinates in the associated table. When selecting this command, you will be asked to confirm that you understand that dragging curves will modify the data in the corresponding tables (as well as all other plots depending on that data). The coordinates of the cursor with respect to the axes of the plot layer are displayed in a text field that floats along with the mouse cursor.

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