R is a widely used open source programming language, which is mainly used for statistical calculation and data analysis. It is characterized by powerful data manipulation ability and graphical analysis function, and can easily realize data visualization, data mining, machine learning and other tasks. The function of R language is one of its core features, and the function is the basic component of the program. Through user-defined functions, a more flexible and efficient data analysis process can be realized.

There are abundant built-in functions and user-defined functions in R language. Built-in functions include basic mathematical functions, statistical functions and graphic functions. User-defined functions can write more perfect analysis programs according to specific data characteristics and analysis requirements. The function of R language not only supports vectorization operation, but also can be directly applied to data frames or data sets, which greatly improves the efficiency of data analysis.

Because of the openness and high customization of R language, the function library of R language is constantly expanding and updating, and the fields involved are becoming more and more extensive. At present, experts, scholars and data analysts in various disciplines are actively using and writing functions in R language, which provides strong technical support for data analysis and academic research. Therefore, it is a very important basic skill for professionals engaged in data analysis and statistical calculation to master the function use and writing skills of R language.