Data Structure - Data Frame

Q

What is a Data Frame?

✍: FYIcenter.com

A

Data Frame is a generalization of matrix where columns may have different data types. Technically, a data frame is a special list.

1. Create a factor object with the data.frame() function -

```> name = c("Lori", "Mike", "Nill", "Sofi")
> sex = factor( c("F", "M", "M", "F") )
> age = c(21, 33, 25, 28)

> frame = data.frame(name, sex, age)
> frame
name sex age
1 Lori   F  21
2 Mike   M  33
3 Nill   M  25
4 Sofi   F  28

> typeof(frame)
[1] "list"

> is.data.frame(frame)
[1] TRUE

> is.list(frame)
[1] TRUE

> is.vector(frame)
[1] FALSE
```

2. Using data frame as a list -

```> length(frame)
[1] 3

> frame[1]
name
1 Lori
2 Mike
3 Nill
4 Sofi

> frame[[1]]
[1] "Lori" "Mike" "Nill" "Sofi"

> frame[[1]][2]
[1] "Mike"
```

3. Using data frame as a matrix -

```> dim(frame)
[1] 4 3

> frame[1,]
name sex age
1 Lori   F  21

> frame[2:3,]
name sex age
2 Mike   M  33
3 Nill   M  25

> frame[,1]
[1] "Lori" "Mike" "Nill" "Sofi"

> frame[, "name"]
[1] "Lori" "Mike" "Nill" "Sofi"
```

A data frame is like a table in a database.

2023-05-31, 357🔥, 0💬