Data frame creation in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a data frame in R?

A data frame is a table-like structure in R that holds data in rows and columns. Each column can have different types like numbers, text, or factors.

beginner

How do you create a simple data frame with columns 'Name' and 'Age' in R?

Use the data.frame() function like this:<br>data.frame(Name = c("Alice", "Bob"), Age = c(25, 30))

beginner

What happens if columns in a data frame have different lengths?

R will give an error because all columns in a data frame must have the same number of rows.

beginner

How can you check the structure of a data frame after creating it?

Use the str() function to see the structure, types, and sample data of the data frame.

beginner

Can a data frame column contain different data types?

No, each column must have the same data type, but different columns can have different types.

Which function is used to create a data frame in R?

A data.frame()

B create.df()

C make.data()

D frame.create()

The correct function to create a data frame in R is data.frame().

What will happen if you try to create a data frame with columns of unequal length?

A R will throw an error

B R will fill missing values with zeros

C R will recycle shorter columns automatically

D R will create a list instead

R requires all columns in a data frame to have the same length; otherwise, it throws an error.

Which of these is a valid way to create a data frame with two columns 'x' and 'y'?

A data.frame(x = c(1,2), y = c('a','b','c'))

B data.frame(x = 1:3, y = c('a', 'b'))

C data.frame(x = 1:3, y = c('a', 'b', 'c'))

D data.frame(x = 1:3, y = 1:2)

Only option D has columns of equal length (3), which is required for data frames.

How do you view the structure of a data frame named df?

A head(df)

B view(df)

C summary(df)

D str(df)

The str() function shows the structure of the data frame including types and sample data.

Can a single column in a data frame contain both numbers and text?

A Yes, columns can mix types freely

B No, each column must have one data type

C Only if you convert the column to a list

D Only if you use factors

Each column in a data frame must have the same data type for all its values.

Explain how to create a data frame in R with three columns: Name, Age, and City.

Think about how you combine vectors into a table.

Describe what happens if you try to create a data frame with columns of different lengths.

Imagine a table where rows must line up.