Creating Advanced Multi-Panel Plots and Data Fitting Routines in qtGrace
qtGrace is a powerful, cross-platform GUI wrapper for the classic Grace (XMGRACE) plotting tool. It combines the robust, publication-quality engine of Grace with a modern user interface. This guide walks you through building complex, publication-ready multi-panel layouts and executing precise data-fitting routines. Designing Multi-Panel Layouts
Multi-panel plots allow you to compare multiple datasets or variables side-by-side without cluttering a single coordinate system. qtGrace organizes these layouts using a grid of independent graphs. Arranging the Grid Navigate to Edit > Arrange graphs from the main menu.
Specify the desired number of Rows and Columns (e.g., a 2×2 grid).
Adjust the Margins (left, right, top, bottom) to control the spacing around the entire plot area.
Set the Spacing (horizontal and vertical) between individual graph panels. Click Apply to generate the new layout. Managing Active Graphs
qtGrace designates the active panel with a visual highlight or outline.
To switch focus: Click directly inside any panel, or use the Graph selector tool in the toolbar.
Independent properties: Every graph panel maintains its own independent axes, scaling, legends, and styling. Creating Shared Axes
For stacked plots sharing a timeline or a common independent variable, eliminating gaps creates a seamless presentation.
Set the vertical or horizontal Spacing to 0.0 in the Arrange graphs menu. Select the inner graph panels. Open Plot > Axis properties.
Hide duplicate tick labels and axis labels on shared edges by unchecking Display tick labels for those specific sides. Importing and Structuring Datasets
Before fitting data across multiple panels, your source files must be properly formatted and assigned to their respective graphs. File Formatting
qtGrace natively reads plain text files (.txt, .dat, .csv). Structure your data in clean columns:
# X-Data Y-Data1 Y-Data2 0.1 1.24 5.61 0.2 2.48 5.12 0.3 3.71 4.89 Use code with caution. Targeted Data Loading Activate the specific target panel by clicking on it. Go to Data > Import > ASCII. Select your data file.
In the import dialog, choose your Load As type (typically Single Set or N-Columns).
Click Accept to render the data strictly within the active panel.
Repeat this process for alternative panels using different files or column selections. Executing Advanced Data Fitting Routines
qtGrace features a built-in mathematical engine capable of performing linear, polynomial, and custom non-linear regression analysis directly on your visual data sets. Linear and Polynomial Fits
Go to Data > Transformations > Interpolate/spline… or Non-linear curve fitting… depending on complexity. For standard regressions, navigate to Data > Transformations > Regression.
Select the specific graph panel and the exact Set you want to fit. Choose the type of regression (e.g., Linear, Polynomial). If choosing Polynomial, define the Degree of the equation.
Click Accept. qtGrace generates a new, smooth dataset representing the fit line and displays the resulting coefficients ( R2cap R squared value, slope, intercept) in the console log. Custom Non-Linear Curve Fitting
When working with custom physics, engineering, or chemical equations (like exponential decays or Gaussian curves):