Editing

MathJet implements several methods for direct, interactive adjustment of graph values. Compared to traditional data visualization programs — where every change to graph shape must originate from the underlying data source — these methods are faster, more convenient, and more intuitive. You work with the visual elements directly, can modify multiple data points at once, and watch linked cells, derived items (graph characteristics, fits, dependent graphs), and the Graph Companion table update in real time.

The Graph Companion window pairs well with editing: it shows the numerical values of graphs and stays synchronized with chart interactions, so changes you make to the visual graph are reflected in the data table the same instant. Keeping it open while editing makes the work more precise.

In many cases there’s a clear mapping between graph shapes and the underlying data. Changes in graph shapes are pushed back to the data sources as modifications to their values, and they propagate through dependent graphs. This makes graph editing a useful tool for what-if analysis and parameter fine-tuning toward a goal.

Data repair

The Data Repair feature lets you draw a replacement segment directly on a 2D graph as a Bezier curve. Useful for filling in dropouts, overriding outliers, or smoothing a noisy region without leaving the chart view.

Enter via Data → Visual Editing → Data Repair or the toolbar button. A red square marker appears and follows the mouse, snapping to the nearest data point on the graph. When the cursor changes to a target symbol, the marker is right on top of a data point — that’s the signal to begin drawing.

Click the left mouse button to place the first control point. Add as many additional control points as you want by clicking — a data symbol appears only at control points placed directly on data points; control points between data points let you shape the curve freely. Press Backspace to remove the last control point you placed. Double-click on a data point to commit the curve.

On commit, the y-values of every data point whose x-coordinate falls within the curve’s x-range are replaced by the Bezier curve’s value at that x. Linked data sources and derived items (graph characteristics, dependent formulas) update automatically.

After committing, you can immediately start drawing another replacement segment without leaving the mode. Esc also aborts an in-progress drawing.

Data repair — drawing a Bezier replacement segment directly on a 2D graph, committing with a double-click, and watching linked data and derived items update.

Data nudging

Data Nudging lets you adjust data point values interactively by dragging them on the graph.

Enter via Data → Visual Editing → Data Nudging or the toolbar button. A semi-transparent circle appears and follows the mouse, snapping to the nearest data point. When the cursor moves close to the focus of the circle, it changes to two opposing arrows — that’s the signal that the marker is in range for dragging.

Click and hold the left mouse button, then drag up or down slowly. The point inside the circle moves with the drag; linked data source values update in real time, and any dependent items (formulas, graph characteristics) follow.

Adjust multiple points at once. The size of the circle controls how many points your next drag affects. Press and hold Shift and scroll the mouse wheel forward to grow the circle. When you drag a point at the focus of an enlarged circle, all points inside the circle move along — but the magnitude of change falls off with distance from the focus, mirroring the way the circle’s color fades from center to edge. Linked cells in the worksheet pick up matching background-color gradients showing each cell’s relative magnitude of change.

Works on 3D surfaces too. Drag a surface point in 3D and all nearby points inside the circle move along, with the same falloff and the same linked-data updates.

Data nudging — single-point and multi-point editing with a draggable circle, in both 2D and 3D, with linked cells highlighting in proportion to the change.

Data spread adjustment

When source data is noisy and the linked graph spreads over a wide range, Data Spread Adjustment makes it easy to change the spread of values without modifying the central trend.

Enter via Data → Visual Editing → Data Spread Adjustment or the toolbar button. As your mouse hits a graph object in the chart, a semi-transparent polygon appears showing the value spread of that graph. Click the left mouse button anywhere inside the polygon — the upper and lower boundary lines of the spread are drawn on the screen. Move the mouse over either boundary line; the cursor changes to two opposing arrows, signaling readiness for adjustment. Press the left mouse button and drag the boundary to compress or expand the spread. Release to commit. Repeat as often as needed.

Linked data sources and derived items (graph characteristics, dependent graphs) update automatically after each adjustment.

Data spread adjustment — modifying the upper or lower boundary of a graph's value spread, with linked data and derived items updating after each adjustment.

Data point eraser

When you spot outliers during exploration that you want to eliminate from the data, the Data Point Eraser removes any data points you select interactively.

Enter via Data → Visual Editing → Data Eraser or the toolbar button. Interactively select the data points you want to remove and watch them disappear from the graph; repeat as needed until you exit the mode.

If you have data points selected before clicking the menu item or toolbar button, those points are erased automatically the instant the mode is entered.

What “erasing” actually does depends on the graph type:

2D plots with categorical x coordinates (e.g., bar, stem). The whole row containing the linked data cell is deleted — both the x-category and the y-value are gone.
Graphs with x values defined, and 3D plots. The program clears the linked data values but doesn’t delete the underlying row, preserving the structure of the data source.

Data point eraser — removing data points interactively, with row-delete versus value-clear behavior depending on graph type.

Data smoothing

Data Smoothing applies a moving-average operation to some or all of the data points in a graph, repeatedly if desired. Useful for taming jagged graphs without rewriting source values one at a time.

Enter via Data → Visual Editing → Data Smoothing or the toolbar button. The scope depends on what’s selected when you click:

Selected data points — the operation is applied only to those points.
Selected graph object (no individual points) — the operation is applied to the entire graph.
Nothing selected — the operation is applied to all graphs in the current chart.

Click the menu item or toolbar button repeatedly to apply the moving-average kernel again for stronger smoothing. Linked data sources and derived items update automatically after each application.

Data smoothing — applying a moving-average kernel to selected points, a whole graph, or every graph in the chart, with repeat-clicks deepening the effect.

Data replacement

Data Replacement swaps out values in your graph using the Replace Graph Data dialog. Use it when you want to replace selected points (or a whole graph) with values from a fitted function or a custom expression.

Enter via Data → Visual Editing → Data Replacement or the toolbar button. The Replace Graph Data dialog opens. Inside it:

The graph selector combo box at the top is automatically set to the name of the first selected graph. Switch graphs from this dropdown if needed.
The Source Data section shows information about the active data points (the current selection, or the whole graph if no points are selected).
The Replacement radio group offers fit types: Constant Value, Linear, Polynomial (with configurable order), Exponential, Logarithmic, Power. When you pick a fit type — say, Polynomial — MathJet automatically calculates the coefficients from the source data and shows the resulting expression in the formula text box.
Custom expression. Type any expression in x (and y for 2D graphs) into the formula text box. The expression is evaluated for each active data point to generate its replacement value. Useful when none of the predefined fits match what you want.

Click OK to apply. Linked data sources and derived items update.

Data replacement — using the Replace Graph Data dialog to swap selected points or whole graphs via a fit type or a custom expression in x and y.