Summarizing a data frame - r

Question

I am trying to take the following data, and then uses this data to create a table which has the information broken down by state.
Here's the data:
> head(mydf2, 10)
lead_id buyer_account_id amount state
1 52055267 62 300 CA
2 52055267 64 264 CA
3 52055305 64 152 CA
4 52057682 62 75 NJ
5 52060519 62 750 OR
6 52060519 64 574 OR
15 52065951 64 152 TN
17 52066749 62 600 CO
18 52062751 64 167 OR
20 52071186 64 925 MN
I've allready subset the states that I'm interested in and have just the data I'm interested in:
mydf2 = subset(mydf, state %in% c("NV","AL","OR","CO","TN","SC","MN","NJ","KY","CA"))
Here's an idea of what I'm looking for:
State Amount Count
NV 1 50
NV 2 35
NV 3 20
NV 4 15
AL 1 10
AL 2 6
AL 3 4
AL 4 1
...
For each state, I'm trying to find a count for each amount "level." I don't necessary need to group the amount variable, but keep in mind that they are are not just 1,2,3, etc
> mydf$amount
[1] 300 264 152 75 750 574 113 152 750 152 675 489 188 263 152 152 600 167 34 925 375 156 675 152 488 204 152 152
[29] 600 489 488 75 152 152 489 222 563 215 452 152 152 75 100 113 152 150 152 150 152 452 150 152 152 225 600 620
[57] 113 152 150 152 152 152 152 152 152 152 640 236 152 480 152 152 200 152 560 152 240 222 152 152 120 257 152 400
Is there an elegant solution for this in R for this or will I be stuck using Excel (yuck!).

Answer 1

Here's my understanding of what you're trying to do:
Start with a simple data.frame with 26 states and amounts only ranging from 1 to 50 (which is much more restrictive than what you have in your example, where the range is much higher).
set.seed(1)
mydf <- data.frame(
state = sample(letters, 500, replace = TRUE),
amount = sample(1:50, 500, replace = TRUE)
)
head(mydf)
# state amount
# 1 g 28
# 2 j 35
# 3 o 33
# 4 x 34
# 5 f 24
# 6 x 49
Here's some straightforward tabulation. I've also removed any instances where frequency equals zero, and I've reordered the output by state.
temp1 <- data.frame(table(mydf$state, mydf$amount))
temp1 <- temp1[!temp1$Freq == 0, ]
head(temp1[order(temp1$Var1), ])
# Var1 Var2 Freq
# 79 a 4 1
# 157 a 7 2
# 391 a 16 1
# 417 a 17 1
# 521 a 21 1
# 1041 a 41 1
dim(temp1) # How many rows/cols
# [1] 410 3
Here's a little bit different tabulation. We are tabulating after grouping the "amount" values. Here, I've manually specified the breaks, but you could just as easily let R decide what it thinks is best.
temp2 <- data.frame(table(mydf$state,
cut(mydf$amount,
breaks = c(0, 12.5, 25, 37.5, 50),
include.lowest = TRUE)))
temp2 <- temp2[!temp2$Freq == 0, ]
head(temp2[order(temp2$Var1), ])
# Var1 Var2 Freq
# 1 a [0,12.5] 3
# 27 a (12.5,25] 3
# 79 a (37.5,50] 3
# 2 b [0,12.5] 2
# 28 b (12.5,25] 6
# 54 b (25,37.5] 5
dim(temp2)
# [1] 103 3

Answer 2

I am not sure if I understand correctly (you have two data.frames mydf and mydf2). I'll assume your data is in mydf. Using aggregate:
mydf$count <- 1:nrow(mydf)
aggregate(data = mydf, count ~ amount + state, length)
Is this what you are looking for?
Note: here count is a variable that is created just to get directly the output of the 3rd column as count.
Alternatives with ddply from plyr:
# no need to create a variable called count
ddply(mydf, .(state, amount), summarise, count=length(lead_id))
Here' one could use any column that exists in one's data instead of lead_id. Even state:
ddply(mydf, .(state, amount), summarise, count=length(state))
Or equivalently without using summarise:
ddply(mydf, .(state, amount), function(x) c(count=nrow(x)))