Direct entry, Data frames

## Inputting Data

R allows users to input data using a wide range methods. - Directly by typing the data into R (using scan()) - Reading external files: txt, csv, SAS, SPSS, Excel.

I encourage you to learn different methods, but we will cover a common and robust use case: handling csv files. For more information follow this advice.

## Inputting Data

### Direct Method

You can directly input data points one by one using scan()
Do it yourself:

x <- scan()
13
2
1.2
3
18
6

x

This is called a base function.

## Inputting Data

### External Files

External files come in various formats and a number of convenience functions are available:

- read.table()

- read.csv()

- read.delim()

Before we need to find out our working directory:\
Do it yourself:

getwd()
[1] "/Users/BIO3DICKIB/Library/Mobile Documents/com~apple~CloudDocs/Github/the-fourth-r/docs"

## Inputting Data

### Setting Paths

You can use dir() to find what is in each directory and setwd() to change to a new working directory.

Do it yourself: We are going to change working directory to the revanent-master folder we put in the OneDrive folder earlier:

dir()
setwd("C://PATH/TO/revanent-master")
dir()

## Do it yourself:

Read the simple.txt data set and store it in a data frame called easy:

easy <- read.table('../data/simple.txt', header = TRUE, sep = "\t")

Let us look at the first 6 lines of the data:

head(easy)
  Deaths PersonYear
1     32      52407
2    104      43248
3    206      28612
4    186      12663
5    102       5317
6      2      18790

There’s also an RStudio command (note uppercase letter) for looking at a data frame:

View(easy)

## Plotting

Now plot the data!

plot(easy)

## Inputting Data

### Comma Separated

Do it yourself: Read the smoking.csv data set and store it in a data frame called smoking:

smoking <- read.csv('../data/smoking.csv', header = TRUE)

Let’s look at the data too:

View(smoking)

## Data Frames

• A data frame is a list of variables, each of the same length but not necessarily of the same type.
• The top line of the table, called the header, contains the column names.
• Each horizontal line afterward denotes a data row, which begins with the name of the row, and then followed by the actual data.

## Built-in Data Frames

• We can also call built-in data frames in R for our tutorials.
• This can be done by using the data() command.
• For example, here is a built-in data frame in R, called mtcars.

## Do it yourself:

Call the R built-in data set mtcars as follows:

data(mtcars)

Let us look at the first 6 lines of the data:

head(mtcars)
                   mpg cyl disp  hp drat    wt  qsec vs am gear carb
Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

  ?mtcars
ls()
[1] "easy"    "mtcars"  "smoking"
Or you can see it in the top right corner of RStudio (Environment tab).