Rearanging Data - r

Question

I am trying to rearrange a data set and then sort it on multiple variables. For example, right now I have something that looks like this:
ID Name Class 1 Class2 Monday 7-8 Monday 8-9
1 Brad Chem Bio Monday 7-8 NA
2 Charlene Acct NA NA Monday 8-9
3 Carly Philosophy Physics NA NA
4 Jess Chem Acct Monday 7-8 Monday 8-9
And sort the data like this:
Class Monday 7-8 Monday 8-9
Acct Jess Charlene, Jess
Bio Brad NA
Chem Brad, Jess Jess
Philosophy NA NA
Physics NA NA
I have tried separating all of the variables into different spreadsheets and then merging them, but I cant figure out how to sort the name based on both class and time and it is proving incredibly difficult to figure out. The actual database is composed of about 70 different time options with 80 different people and 150 different class names (chem, bio, etc), so I cant go in and create this individually

Answer 1

a tidyr solution:
df1 %>%
gather(class_col,Class,'Class.1','Class2') %>%
filter(!is.na(Class)) %>%
gather(date_col,date,'Monday.7.8','Monday.8.9') %>%
group_by(Class,date) %>%
summarize(Name = paste(Name,collapse=", ")) %>%
spread(date,Name) %>%
select(-`<NA>`)
# # A tibble: 5 x 3
# # Groups: Class [5]
# Class `Monday 7-8` `Monday 8-9`
# * <chr> <chr> <chr>
# 1 Acct Jess Charlene, Jess
# 2 Bio Brad <NA>
# 3 Chem Brad, Jess Jess
# 4 Philosophy <NA> <NA>
# 5 Physics <NA> <NA>

Answer 2

Here is some base R code for this task:
dat <- data.frame(
name=c("Brad", "Charlene", "Carly", "Jess"),
class1=c("Chem", "Acct", "Philosophy", "Chem"),
class2=c("Bio", NA, "Physics", "Acct"),
monday7.8=c("monday7.8", NA, NA, "monday7.8"),
monday8.9=c(NA, "monday8.9", NA, "monday8.9"),
stringsAsFactors=FALSE
)
classes <- c("Chem", "Acct", "Philosophy", "Physics")
times <- c("monday7.8", "monday8.9")
ret <- expand.grid(class=classes, time=times, stringsAsFactors=FALSE)
one_alloc <- function(cl, tm, dat) {
idx <- which(!is.na(dat[,tm]) & (dat[,"class1"]==cl | dat[,"class2"]==cl))
if(length(idx)>0) return(paste(dat[idx,"name"], collapse=", ")) else return(NA)
}
one_alloc <- Vectorize(one_alloc, vectorize.args=c("cl", "tm"))
ret[,"names"] <- one_alloc(cl=ret[,"class"], tm=ret[,"time"], dat=dat)
ret <- reshape(ret, timevar="time", idvar="class", direction="wide")
ret