# How to Select Unique Rows in a Data Frame in R

You can use the following methods to select unique rows from a data frame in R:

Method 1: Select Unique Rows Across All Columns

```library(dplyr)

df %>% distinct()```

Method 2: Select Unique Rows Based on One Column

```library(dplyr)

df %>% distinct(column1, .keep_all=TRUE)
```

Method 3: Select Unique Rows Based on Multiple Columns

```library(dplyr)

df %>% distinct(column1, column2, .keep_all=TRUE)```

This tutorial explains how to use each method in practice with the following data frame:

```#create data frame
df <- data.frame(team=c('A', 'A', 'A', 'A', 'B', 'B', 'B', 'B'),
position=c('G', 'G', 'F', 'F', 'G', 'G', 'F', 'F'),
points=c(10, 10, 8, 14, 15, 15, 17, 17))

#view data frame
df

team position points
1    A        G     10
2    A        G     10
3    A        F      8
4    A        F     14
5    B        G     15
6    B        G     15
7    B        F     17
8    B        F     17
```

## Example 1: Select Unique Rows Across All Columns

The following code shows how to select rows that have unique values across all columns in the data frame:

```library(dplyr)

#select rows with unique values across all columns
df %>% distinct()

team position points
1    A        G     10
2    A        F      8
3    A        F     14
4    B        G     15
5    B        F     17
```

We can see that there are five unique rows in the data frame.

Note: When duplicate rows are encountered, only the first unique row is kept.

## Example 2: Select Unique Rows Based on One Column

The following code shows how to select unique rows based on the team column only.

```library(dplyr)

#select rows with unique values based on team column only
df %>% distinct(team, .keep_all=TRUE)

team position points
1    A        G     10
2    B        G     15
```

Since there are only two unique values in the team column, only the rows with the first occurrence of each value are kept.

Note: The argument .keep_all=TRUE tells R to keep all other columns in the output.

## Example 3: Select Unique Rows Based on Multiple Columns

The following code shows how to select unique rows based on the team and position columns only.

```library(dplyr)

#select rows with unique values based on team and position columns only
df %>% distinct(team, position, .keep_all=TRUE)

team position points
1    A        G     10
2    A        F      8
3    B        G     15
4    B        F     17
```

Four rows are returned, since there are four unique combinations of values across the team and position columns.