R – Create DataFrame
To create DataFrame in R programming language, call data.frame() function and provide necessary initial data.
In this tutorial, we will go through the syntax of data.frame() function, and how to use it to create a DataFrame, with examples.
Syntax
The syntax of data.frame() function is
data.frame(..., row.names = NULL, check.rows = FALSE,
check.names = TRUE, fix.empty.names = TRUE,
stringsAsFactors = FALSE) The default values for the arguments are given in the above definition itself.
where
| Arguemnt | Description |
|---|---|
| … | Multiple arguments. Each argument is usually of the form value or tag = value. value could be a vector. |
| row.names | An integer or character string. This specifies a column to be used as row names. |
| check.rows | If TRUE, then the rows are checked for consistency of length and names. |
| check.names | If TRUE then the names of the variables in the DataFrame are checked to ensure that they are syntactically valid variable names and are not duplicated. |
| fix.empty.names | If TRUE, the arguments which are unnamed, get an automatically constructed name or rather name "". |
| stringsAsFactors | If TRUE, character vectors be converted to factors. |
Examples
In the following examples, we will go through different scenarios of creating a DataFrame in R, based on the argument values.
1. Create a simple DataFrame
In the following program, we create a DataFrame from three vectors. These vectors will be used as columns. We provide the vectors in the form tag = value. tag would be considered as column name, and the value would be considered as column values.
example.R
df <- data.frame(a = c(41, 42, 43, 44),
b = c(45, 46, 47, 48),
c = c(49, 50, 51, 52))
print(df) Output
a b c 1 41 45 49 2 42 46 50 3 43 47 51 4 44 48 52
a, b, c are column names. Since, no row names are provided, default values of 1, 2, 3, .. are considered.
If no tag is provided for the values in arguments, then R would generate column name automatically for the argument.
In the following program, the first argument to data.frame() function is a vector with no tag / column name.
example.R
df <- data.frame(c(41, 42, 43, 44),
b = c(45, 46, 47, 48),
c = c(49, 50, 51, 52))
print(df) Output
c.41..42..43..44. b c 1 41 45 49 2 42 46 50 3 43 47 51 4 44 48 52
Since the argument is just a value with no tag / column name, R generated a column name, which in this case is c.41..42..43..44..
2. Create DataFrame with Row Names
In the following program, we create a DataFrame with specific row names. We pass a vector for row.names argument in the data.frame() function call.
example.R
df <- data.frame(a = c(41, 42, 43, 44),
b = c(45, 46, 47, 48),
c = c(49, 50, 51, 52),
row.names = c('p', 'q', 'r', 's'))
print(df) Output
a b c p 41 45 49 q 42 46 50 r 43 47 51 s 44 48 52
Conclusion
In this R Tutorial, we learned how to create a DataFrame in R using data.frame() function, with the help of examples.