Clicking with SELECT on the iconbar icon, or on the New option in the iconbar menu, will open a new data input window. GraphDraw can have several of these windows active at any one time. The window is shown below.
The window as opened will have two columns for the x and y values. Clicking the mouse in an appropriate cell will set the caret ready for text input. Tab will move from one cell to the next. Return will do the same, but in addition, when in the rightmost cell, a new row will be added when Return is pressed. The result of entering data may be as shown below.
For general editing of the data most of the expected special keypresses for navigation, etc., are available. To clear a cell, use Ctrl-U. To delete a complete row, use Ctrl-Shift-Delete. To insert a new blank row, use Ctrl-Shift-Insert. The full set of keypresses are described below.
Double clicking a previously saved data file will load it into a new data input window (assuming the limit of open windows has not been reached). A previously saved data file may also be dragged to the iconbar icon, whereupon the data will be loaded into a new input window.
The behaviour on dragging a file into an already open edit window depends upon whether you have the option "Drag to edit window appends data" ticked. This option can be found in Choices... from the iconbar menu. If the option is ticked (selected) then dragging a data file to the edit window will add the data to that which is already present. This allows you to combine two or more sets of data into one dataset. If the option is not ticked, then the new data will be loaded into a new input window as above.
!GraphDraw can load files of comma, TAB, or space separated ASCII data, as long as the filetype is either text, data, or CSV, and so it is possible to set up other applications to produce data files of the correct form. Contact the author if you need any advice on integrating your own applications with GraphDraw or MultiPlot.
The menu attached to the data input window is shown to the right.
Once a GraphDraw data file has been saved, then double clicking on it in a filer window will reload it in to GraphDraw. If the application has been seen by the filer, or been filer_booted, then GraphDraw will be launched if not already running. The saved data file can also be reloaded into GraphDraw by dragging its file icon from a filer window to the iconbar icon.
In the case of joined points, each point is joined to the next point by a straight line. While this is not the usual "scientific" way of doing things, it can be useful under certain circumstances.
A submenu is also available which allows the further options of
In the latter cases, an error will be generated if one or more of the values to be logged is zero or negative.
When the chosen fit has been completed, a window will open in which is shown the results of the fitting procedure.
y = u + vx + wx2
This is a useful technique for fitting data to a simple curve. A window will open showing the calculated values of the coefficients u, v and w.
y = a + bx + cx2
y = a + bx + cx2 + dx3
y = a + bx + cx2 + dx3 + ex4
y = a + bx + cx2 + dx3 + ex4 + fx5
y = a + bx + cx2 + dx3 + ex4 +
fx5 + gx6
It also leads to a submenu which allows you to select a particular order to force the program to calculate that specific order polynomial. The option 'All' is also available, which has the same action as selecting the polynomial option in the root menu, i.e. the program will try all possible orders (2 to 6) and report the one which gives the smallest deviation. Some of the higher order options may be greyed out if there are not enough data points to allow the fit to be calculated. A scrollable window will open showing the results of the calculation.
A value of almost 1.0 (e.g. 0.9999) will try to force the line to pass through every point. A very small value, e.g. 0.0001, will produce something approaching a straight line through the data points. Note that the program will not allow you to enter a value of exactly 0.0 or 1.0, since this would create a "divide by zero error" during the calculation. Pressing the RETURN key or clicking on the Calculate button will carry out the calculation and a graph window will open to display a graph of the cubic spline curve through the data points. For this plot, it requires the data to be sorted in increasing order of x. The program automatically sorts the data in ascending order of x values before carrying out the spline routine (note that it will not change the order of the data in the data edit window).
Many of the standard key actions are available in the input window.
Left arrow | Move caret left by one character within the current field. |
Shift left arrow | Move caret to left of data in current cell, unless already at left, when caret moves to previous cell in row. |
Control left arrow or Home | Move caret to end of data in leftmost cell of current row. |
Right arrow | Move caret right by one character within the current field. |
Shift right arrow | Move caret to right of data in current cell, unless already at right, when caret moves to next cell in row. |
Control right arrow or End | Move caret to end of data in rightmost cell of current row. |
Down arrow | Move caret down one row. |
Up arrow | Move caret up one row. |
Page down or Shift down arrow | Move caret down by 10 lines, or to bottom line if less than ten lines from bottom. |
Page up or Shift up arrow | Move caret up by 10 lines, or to top line if less than ten lines from top. |
Control down arrow | Move caret to bottom line. |
Control up arrow | Move caret to top line. |
Tab | Move caret to next field. If at end of row, move to left field of next row. |
Shift Tab | Caret moves to previous cell in row. |
Return | Move caret to next field. If at end of row, move to left field of next row. If at end of bottom row, create a new row and move to left field. |
Control U | Clear the contents of the current cell. |
Backspace | Delete character to left of caret. |
Delete | Delete character to right of caret. |
Control shift Delete | Delete the complete row of data and close up the rows. |
Control shift Insert | Insert a new blank row above the current caret row. |
These pages are best viewed in a CSS compliant browser. For RISC OS, Netsurf would be the browser of choice.
Choices
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Index |
Results of fitting
GraphDraw is © Chris Johnson, 2014
Email:chris@chris-johnson.org.uk
This document last modified on 15th August 2015