Table of Contents
The Column in R is not necessarily a date. It can contain various types of data, including numerical values, characters, and logical values. However, if the data in the column follows a specific date format, such as YYYY-MM-DD, then it can be considered a date column. For example, a column containing dates in the format of “2020-01-01” or “Jan 1, 2020” would be considered a date column, while a column with values such as “Monday” or “True” would not. Ultimately, whether a column in R is a date depends on the type of data it contains and how it is formatted.
You can use the is.Date function from the lubridate package in R to quickly check if a data frame column is a date.
There are two common ways to use this function in practice:
Method 1: Check if One Specific Column is Date
library(lubridate) #check if 'sales' column is date is.Date(df$sales)
Method 2: Check if Each Column in Data Frame is Date
library(lubridate) #check if each column in data frame is date sapply(df, is.Date)
The following examples show how to use each method in practice with the following data frame in R:
#create data frame df <- data.frame(date = as.Date('2023-01-01') + 0:9, sales = c(12, 14, 7, 7, 6, 8, 10, 5, 11, 8), refunds = c(2, 0, 0, 3, 2, 1, 1, 0, 0, 4)) #view data frame df date sales refunds 1 2023-01-01 12 2 2 2023-01-02 14 0 3 2023-01-03 7 0 4 2023-01-04 7 3 5 2023-01-05 6 2 6 2023-01-06 8 1 7 2023-01-07 10 1 8 2023-01-08 5 0 9 2023-01-09 11 0 10 2023-01-10 8 4
Example 1: Check if One Specific Column is Date
The following code shows how to check if the sales column is a date:
library(lubridate) #check if 'sales' column is date is.Date(df$sales) [1] FALSE
The function returns FALSE, which tells us that the sales column is not a date column.
Example 2: Check if Each Column in Data Frame is Date
The following code shows how to check if each column in the data frame is a date:
library(lubridate) #check if each column in data frame is date sapply(df, is.Date) date sales refunds TRUE FALSE FALSE
The output returns either TRUE or FALSE for each column in the data frame to indicate if it is a date.
From the output we can see:
- The date column is a date.
- The sales column is not a date.
- The refunds column is not a date.
Note: If you’d like to see the class of each column in the data frame, you can use the sapply function combined with the class function as follows:
#view class of each column in data frame
sapply(df, class)
date sales refunds
"Date" "numeric" "numeric"
The output displays the class of each column in the data frame.
Related:
Additional Resources
The following tutorials explain how to perform other common tasks in R:
How to Plot a Time Series in R
How to Extract Year from Date in R