data frame vs matrix

Question

I am new to R and am still trying to understand when should a data.frame be used and when should a matrix be used.

I know that both of them are multi-dimensional data types, i want to know when to use which data type.

Answer 1

Yes, both matrix and data.frame are multidimensional data-types and both of them store data in rectangular format.

This is where the difference comes:

A 'matrix' stores only homogenous data while a 'data.frame' stores heterogenous data.

Let me demonstrate this with an example:

Matrix:

temperature<-c(20,22,20,25,20)

humidity<-c(54,50,45,43,50)

climate<-matrix(c(temperature,humidity),nrow=5)

 climate
     [,1] [,2]
[1,]   20   54
[2,]   22   50
[3,]   20   45
[4,]   25   43
[5,]   20   50

This 'climate' matrix takes only numeric vectors and hence it is homogenous.

Data-Frame:

rain<-c(T,F,F,F,T)

rainfall<-data.frame(temp=temperature,humid=humidity,rain=rain)

rainfall
  temp humid  rain
1   20    54  TRUE
2   22    50 FALSE
3   20    45 FALSE
4   25    43 FALSE
5   20    50  TRUE

'rainfall' is a data.frame which consists of heterogenous entries.