### Some example solutions for Free Response Question on Test 2

# (a)
library(readr)
class_scores <- readr::read_csv(file="Z:/My_Documents/teaching/stat_220/classresults.csv", col_names = F)
#or
class_scores <- read.csv(file="Z:/My_Documents/teaching/stat_220/classresults.csv", header = F)
names(class_scores) <- c('name', 'major', 't1grade', 't1date', 't2grade', 't2date')

library(lubridate)

# (b)
class_scores %>%
mutate(
conv_t1date = ymd(t1date),
conv_t2date = ymd(t2date)
)
# or:
conv_t1date = ymd(t1date);
conv_t2date = ymd(t2date)

# Just to check:
# str(conv_t2date)

# t2date-t1date # won't work

conv_t2date-conv_t1date

# Does 'interval' work?
# doesn't quite work because this is a vector...
#interval(class_scores$conv_t2date,class_scores$conv_t1date)/ddays(1)
interval(conv_t2date[1],conv_t1date[1])/ddays(1) #works one element at a time...  would need to 'map' or 'apply' to handle iteration

mean(today()-conv_t2date)

#(c)
str(class_scores)
# or
glimpse(class_scores)
#or
summary(class_scores)


#(d)
test_plot <- ggplot(class_scores,aes(x=t1grade,y=t2grade,color=major)) + geom_point()
 library(gganimate)
 library(transformr)
 test_animation <- test_plot +
   transition_states(major) 
 
 animate(test_animation)