# Groupby maximum in R

Groupby maximum in R can be accomplished by aggregate() or group_by() function of dplyr package. Groupby maximum of multiple column and single column in R is accomplished by multiple ways some among them are group_by() function of dplyr package in R and aggregate() function in R.  Let’s see how to

• Groupby max of single column in R
• Groupby max of multiple columns in R
• Groupby maximum using aggregate() function
• Groupby maximum using group_by() function.

Groupby maximum in R and its functionality has been pictographically represented as shown below

First let’s create a dataframe

```df1= data.frame(Name=c('James','Paul','Richards','Marico','Samantha','Ravi','Raghu','Richards','George','Ema','Samantha','Catherine'),
Sales=c(14,24,31,12,13,7,9,31,18,16,18,14))
df1
```

df1 will be

#### Groupby using aggregate() syntax:

aggregate(x, by, FUN, …, simplify = TRUE, drop = TRUE)
 X an R object, Mostly a dataframe by a list of grouping elements, by which the subsets are grouped by FUN a function to compute the summary statistics simplify a logical indicating whether results should be simplified to a vector or matrix if possible drop a logical indicating whether to drop unused combinations of grouping values.

#### Groupby maximum of single column in R:

Method 1:

Aggregate function along with parameter by – by which it is to be grouped and function max is mentioned as shown below

```# Groupby max of single column

aggregate(df1\$Sales, by=list(df1\$State), FUN=max)
```

so the grouped dataframe will be

#### Method 2: group_by() using dplyr

group_by() function takes “state” column as argument  summarise() uses max() function to find maximum of sales.

```library(dplyr)
df1 %>% group_by(State) %>% summarise(Max_sales = max(Sales))
```

so the grouped dataframe with maximum of sales calculated will be

#### Method 1:

Aggregate function which is grouped by “State” and “Name”, along with function max is mentioned as shown below

```# Groupby max of multiple columns

aggregate(df1\$Sales, by=list(df1\$State,df1\$Name), FUN=max)
```

so the grouped dataframe will be

#### Method 2: groupby using dplyr

group_by() function takes “State” and “Name” column as argument and groups by these two columns and summarise() uses max() function to find maximum of a sales.

```library(dplyr)
df1 %>% group_by(State,Name) %>% summarise(Max_sales = max(Sales))
```

so the grouped dataframe by “State” and “Name” column with aggregated max of sales will be

For further understanding of group_by() function in R using dplyr one can refer the dplyr documentation

#### Related Topics:

## Author

• With close to 10 years on Experience in data science and machine learning Have extensively worked on programming languages like R, Python (Pandas), SAS, Pyspark.