You can use the following methods to find the earliest date in a column of a data frame in R:
Method 1: Find Earliest Date in Column
min(df$date_column)
Method 2: Find Row with Earliest Date in Column
df[which.min(df$date), ]
The following examples shows how to use this syntax in practice with the following data frame:
#create data frame df <- data.frame(date=as.Date(c('2022-04-01','2022-02-12','2022-06-13','2022-02-04', '2022-07-01','2022-02-19','2022-12-03','2022-04-04')), sales = c(12, 15, 24, 24, 14, 19, 12, 38)) #view data frame df date sales 1 2022-04-01 12 2 2022-02-12 15 3 2022-06-13 24 4 2022-02-04 24 5 2022-07-01 14 6 2022-02-19 19 7 2022-12-03 12 8 2022-04-04 38
Example 1: Find Earliest Date in Column
We can use the following code to find the earliest date in the date column of the data frame:
#find earliest date in 'date' column
min(df$date)
[1] "2022-02-04"
From the output we can see that the earliest date in the date column is 2/4/2022.
Note: If you want to find the most recent date, simply change min to max in the code.
Example 2: Find Row with Earliest Date in Column
We can use the following code to find the row with the earliest date in the date column of the data frame:
#find row with earliest date in 'date' column df[which.min(df$date), ] date sales 4 2022-02-04 24
The output displays the entire row that contains the earliest date in the date column.
For example, we can see the following values in this row:
- date: 2022-02-04
- sales: 24
Note: If you want to find the row with the most recent date, simply change which.min() to which.max() in the code.
Additional Resources
The following tutorials explain how to perform other common operations in R:
How to Generate a Sequence of Dates in R
How to Convert Strings to Dates in R
How to Calculate Number of Months Between Dates in R
