• This Shiny app allows users to interactively build linear models.
• It uses the trees dataset (Girth vs Volume).
• Users can brush points on the plot to select data for modeling.

• UI:
  • Displays slope and intercept.
  • Shows a plot with brushing enabled.
• Server:
  • Reactively builds a model from brushed points.
  • If fewer than 2 points are selected, no model is created.

• library:
  • Uses ggplot2 for better visuals: refer to server.R file
• functions used:
  • geom_point() for data points.
  • geom_smooth(method = “lm”) for regression line. Brushed points are highlighted in red. Confidence interval is shown around the regression line.

• Features of the app:
  • Slope and Intercept displayed in sidebar.
  • Plot updates dynamically:
  • Original data in black.
  • Brushed points in red.
  • Regression line in blue with confidence interval.

```r model <- reactive({ brushed_data <- brushedPoints(trees, input$brush1, xvar = “Girth”, yvar = “Volume”) if(nrow(brushed_data) < 2) return(NULL) lm(Volume ~ Girth, data = brushed_data) })