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How to count the number of occurences in a column using dplyr

I'm trying to count the number of occurences in a single column. Here is a snippet of the df I'm working with: enter image description here

Here is the code I have so far:

my_df$day <- weekdays(as.Date(my_df$deadline))
most_common_day <- my_df %>%
arrange(day) %>%
filter(day == "Friday") %>%
select(day)

So the main goal is to get which weekday is the most common. Any suggestions?

Solution

  • There are various ways to count the number of occurrences in R. The basic R method is table():

    table(my_df$day)
#   Friday    Monday  Saturday    Sunday  Thursday   Tuesday Wednesday 
#        4         6         8        11         6         5        10

    The dplyr approach can be with count():

    count(my_df, day)
#        day  n
#1    Friday  4
#2    Monday  6
#3  Saturday  8
#4    Sunday 11
#5  Thursday  6
#6   Tuesday  5
#7 Wednesday 10

    You can also use tally() from dplyr but you will also need group_by():

    my_df %>% group_by(day) %>% tally
#        day  n
#1    Friday  4
#2    Monday  6
#3  Saturday  8
#4    Sunday 11
#5  Thursday  6
#6   Tuesday  5
#7 Wednesday 10

    To get the most common day(s), you can do:

    # when using table()
names(table(my_df$day))[table(my_df$day) == max(table(my_df$day))]
#[1] "Sunday"

# when using count()
count(my_df, day) %>% slice_max(n)
#     day  n
#1 Sunday 11


# when using tally()
my_df %>% group_by(day) %>% tally %>% slice_max(n)
## A tibble: 1 x 2
#  day        n
#  <fct>  <int>
#1 Sunday    11