You can use the following functions from the lubridate package in R to quickly find the day of the week:
Method 1: Find Numeric Day of Week (Assuming Week Starts on Sunday)
wday(df$date_column)
Method 2: Find Numeric Day of Week (Assuming Week Starts on Monday)
wday(df$date_column, week_start=1) Method 3: Find Character Day of Week (Using Abbreviated Labels)
wday(df$date_column, label=TRUE) Method 4: Find Character Day of Week (Using Full Weekday Labels)
wday(df$date_column, label=TRUE, abbr=FALSE)
The following examples show how to use each method in practice with the following data frame:
library(lubridate) #create data frame df frame(date=c('2020-10-11', '2020-10-19', '2020-10-31'), sales=c(435, 768, 945)) #view data frame df date sales 1 2020-10-11 435 2 2020-10-19 768 3 2020-10-31 945
Method 1: Find Numeric Day of Week (Assuming Week Starts on Sunday)
The following code shows how to find the numeric day of the week of the values in the ‘date’ column:
#find day of week
df$weekday #view updated data frame
df
date sales weekday
1 2020-10-11 435 1
2 2020-10-19 768 2
3 2020-10-31 945 7
Note that 1 indicates a Sunday, 2 indicates a Monday, and so on.
Method 2: Find Numeric Day of Week (Assuming Week Starts on Monday)
The following code shows how to find the numeric day of the week (assuming a week starts on Monday) of the values in the ‘date’ column:
#find day of week
df$weekday 1)
#view updated data frame
df
date sales weekday
1 2020-10-11 435 7
2 2020-10-19 768 1
3 2020-10-31 945 6
In this scenario, a 1 indicates a Monday, 2 indicates a Tuesday, and so on.
Method 3: Find Character Day of Week (Using Abbreviated Labels)
The following code shows how to find the abbreviated character day of the week of the values in the ‘date’ column:
#find day of week
df$weekday TRUE)
#view updated data frame
df
date sales weekday
1 2020-10-11 435 Sun
2 2020-10-19 768 Mon
3 2020-10-31 945 Sat
Method 4: Find Character Day of Week (Using Full Weekday Labels)
The following code shows how to find the character day of the week (using full weekday labels) of the values in the ‘date’ column:
#find day of week
df$weekday TRUE, abbr=FALSE)
#view updated data frame
df
date sales weekday
1 2020-10-11 435 Sunday
2 2020-10-19 768 Monday
3 2020-10-31 945 Saturday Note: You can find the complete documentation for the lubridate wday() function here.
Additional Resources
The following tutorials explain how to perform other common operations with dates in R:
How to Extract Year from Date in R
How to Convert Date to Numeric in R
How to Sort a Data Frame by Date in R
How to Aggregate Daily Data to Monthly and Yearly in R