FRApp is an R package and an R-based Shinyapplication providing a user-friendly interactive interface tostreamline the data analysis derived by fitting nonlinear mixed-effectsregression models with an asymptotic exponential functional relationshipon data with a hierarchical structure. The package provides acomprehensive suite of tools tailored for efficient data analysis andvisualization.
The package includes data from Fluorescence Recovery AfterPhotobleaching (FRAP) experiments on actin dynamics in dendriticspines.
To explore all the functionalities ofFRApp, acomprehensive guide is available in a dedicated vignette.
To use theFRApp application first download andinstall R and RStudio fromposit.co.
You can install the package from the CRAN executing the followingcommands from the RStudio console:
install.packages("FRApp")You can install the development version ofFRAppfromGitHub with:
# install.packages("devtools")devtools::install_github("gioiadc/FRApp")To load the package and make the functions available to be used runthe command:
library(FRApp)You must execute this command every time you restart RStudio.
To launch the Shiny app, copy and paste the following code in theconsole:
FRApp()The application opens automatically in the browser.
FRApp allows you to:
load the data
estimate and compare exponential mixed-effects models
print a model report
export the data and the model corresponding objects.
TheFit the model button allows you to estimate themodel. At the end of the estimation process, the following objects willappear on the right side of the application:
summary information on the model
diagnostic plots: scatterplot of residuals vs. estimated valuesand quantile-quantile plot of the residuals
approximate 95% confidence intervals of the parameters ofinterest.
Model fitting is performed with the functionnlme.
You can save models for model comparison with the buttonAddto model list in theModel list section. Saved modelsmust have different names. When multiple models are saved, the table atthe bottom of the page displays comparisons between the saved modelsusing AIC, BIC, and likelihood ratio test criteria.
TheReset model list button allows you to delete thesaved models from the list.
From the drop-down menu in theDownload section, it ispossible to select a model saved in the model list and download a reportand some model’s objects.
In theDownload section, theReport buttonallows you to export the results printed in the application (modelsummary, residual graphs, and intervals) into a PDF document.
TheRData button allows you to export an RData filecontaining six objects:
data: the dataset in the format used for the analysis
fit: the output of the estimated model
pred: the values estimated by the model
CI: the approximate 95% confidence intervals
resid: the residuals of the model
raneff: the random effects available at the differenthierarchical levels.
As a reference for the construction of the model and the differentoptions to specify, we refer to the book: Pinheiro, J., & Bates, D.(2006). Mixed-effects models in S and S-PLUS. Springer science &business media.
As a reference for the FRAP data analysis example: Di Credico, G.,Pelucchi, S., Pauli, F. et al. Nonlinear mixed-effects models to analyzeactin dynamics in dendritic spines.Scientific Reports 15, 5790(2025).https://doi.org/10.1038/s41598-025-87154-w