# rowwise()
# need to use this because some calculations cannot be done across rows, like mean--which is done column-wise
# starts_with
# ends_with
# trial 1
df1 <- starwars %>%
mutate(mass_1 = mass,
mass_2 = mass,
mass_3 = mass) %>%
mutate(a_homeworld = homeworld,
b_homeworld = homeworld,
c_homeworld = homeworld) %>%
relocate(mass, .before = "mass_1") %>%
relocate(homeworld, .before = "a_homeworld")
# NOT RUN -----
#
# EXAMPLE
#
# rowwise() %>%
# mutate(
# sum = sum(c_across(w:z))
######
# rowwise() %>%
# mutate(
# sum = sum(c_across(cols = starts_with()))
# ANALYZE -----
df2 <- df1 %>%
rowwise() %>%
mutate(sum_mass = sum(c_across(cols = starts_with("mass"))))
# GOOD
df3 <- df1 %>%
rowwise() %>%
mutate(sum_mass = sum(c_across(starts_with("mass")))) # excluded `cols =`
df4 <- df3 %>%
rowwise() %>%
# mutate(count_homeworld = sum
## How to count values, 0/1, across rows?