6  Final Exercise

Author

Perry S

6.1 Final Exercise

Using pipes, modify the df_wq data frame as so:

  • assign it to a new object named df_new

  • filter Date to 2021 data only

  • select only the Station, Date, Chla, and Pheophytin columns

  • mutate Station in-place so it’s a factor column

Challenge:

Modify the df_new data frame as so:

  • mutate Chla so it’s +20 specifically for the case when the month is April and the station is P8

    • Hint: April is the 4th month

  • assign it to the object df_new (ie. the same name)

    • can you access the “original” df_new now? what happens if you re-run the code?
Code
df_new <- df_wq %>%
  filter(Date > '2020-12-31' & Date < '2022-12-31') %>% # can also use lubridate
  select(c(Station, Date, Chla, Pheophytin)) %>%
  mutate(Station = factor(Station))

glimpse(df_new)
Code
df_new <- df_new %>%
  mutate(
    Chla = case_when(
      month(Date) == 04 & Station == 'P8' ~ Chla + 20,
      TRUE ~ Chla
    )
  )

df_new