Parameterized reports in R Programming

Introduction

Parameterized reports let you create reports that change based on input values. This helps you reuse the same report for different data or questions.

You want to generate sales reports for different months without rewriting the report.

You need to create a report that shows data for a specific customer chosen by the user.

You want to filter a report by date range entered by the user.

You want to create a summary report that changes based on a selected product category.

Syntax

R Programming

library(rmarkdown)
rmarkdown::render(input = "report.Rmd", params = list(param1 = value1, param2 = value2))

The params argument passes values to the report.

Inside the R Markdown file, you define parameters in the YAML header.

Examples

This example defines a parameter month with a default value. The report prints the month.

R Programming

---
title: "Sales Report"
params:
  month: "2023-01"
output: html_document
---

```{r}
print(params$month)
```

This runs the report with the month parameter set to "2023-02".

R Programming

rmarkdown::render(
  input = "report.Rmd",
  params = list(month = "2023-02")
)

Sample Program

This report greets the person whose name is passed as a parameter. The R console command runs the report with the name "Alice".

R Programming

---
title: "Greeting Report"
params:
  name: "Friend"
output: html_document
---

```{r}
cat(paste0("Hello, ", params$name, "! Welcome to your report."))
```

# In R console:
rmarkdown::render("greeting_report.Rmd", params = list(name = "Alice"))

Important Notes

Parameters must be declared in the YAML header of the R Markdown file.

You can pass multiple parameters as a list to rmarkdown::render().

Using parameters makes your reports flexible and reusable.

Summary

Parameterized reports let you customize report content without changing the code.

Define parameters in the YAML header and pass values when rendering.

This helps create dynamic, reusable reports for different inputs.