Summarizing a dataframe by date and group - r

Question

I am trying to summarize a data set by a few different factors. Below is an example of my data:
household<-c("household1","household1","household1","household2","household2","household2","household3","household3","household3")
date<-c(sample(seq(as.Date('1999/01/01'), as.Date('2000/01/01'), by="day"), 9))
value<-c(1:9)
type<-c("income","water","energy","income","water","energy","income","water","energy")
df<-data.frame(household,date,value,type)
household date value type
1 household1 1999-05-10 100 income
2 household1 1999-05-25 200 water
3 household1 1999-10-12 300 energy
4 household2 1999-02-02 400 income
5 household2 1999-08-20 500 water
6 household2 1999-02-19 600 energy
7 household3 1999-07-01 700 income
8 household3 1999-10-13 800 water
9 household3 1999-01-01 900 energy
I want to summarize the data by month. Ideally the resulting data set would have 12 rows per household (one for each month) and a column for each category of expenditure (water, energy, income) that is a sum of that month's total.
I tried starting by adding a column with a short date, and then I was going to filter for each type and create a separate data frame for the summed data per transaction type. I was then going to merge those data frames together to have the summarized df. I attempted to summarize it using ddply, but it aggregated too much, and I can't keep the household level info.
ddply(df,.(shortdate),summarize,mean_value=mean(value))
shortdate mean_value
1 14/07 15.88235
2 14/09 5.00000
3 14/10 5.00000
4 14/11 21.81818
5 14/12 20.00000
6 15/01 10.00000
7 15/02 12.50000
8 15/04 5.00000
Any help would be much appreciated!

Answer 1

It sounds like what you are looking for is a pivot table. I like to use reshape::cast for these types of tables. If there is more than one value returned for a given expenditure type for a given household/year/month combination, this will sum those values. If there is only one value, it returns the value. The "sum" argument is not required but only placed there to handle exceptions. I think if your data is clean you shouldn't need this argument.
hh <- c("hh1", "hh1", "hh1", "hh2", "hh2", "hh2", "hh3", "hh3", "hh3")
date <- c(sample(seq(as.Date('1999/01/01'), as.Date('2000/01/01'), by="day"), 9))
value <- c(1:9)
type <- c("income", "water", "energy", "income", "water", "energy", "income", "water", "energy")
df <- data.frame(hh, date, value, type)
# Load lubridate library, add date and year
library(lubridate)
df$month <- month(df$date)
df$year <- year(df$date)
# Load reshape library, run cast from reshape, creates pivot table
library(reshape)
dfNew <- cast(df, hh+year+month~type, value = "value", sum)
> dfNew
hh year month energy income water
1 hh1 1999 4 3 0 0
2 hh1 1999 10 0 1 0
3 hh1 1999 11 0 0 2
4 hh2 1999 2 0 4 0
5 hh2 1999 3 6 0 0
6 hh2 1999 6 0 0 5
7 hh3 1999 1 9 0 0
8 hh3 1999 4 0 7 0
9 hh3 1999 8 0 0 8

Answer 2

Try this:
df$ym<-zoo::as.yearmon(as.Date(df$date), "%y/%m")
library(dplyr)
df %>% group_by(ym,type) %>%
summarise(mean_value=mean(value))
Source: local data frame [9 x 3]
Groups: ym [?]
ym type mean_value
<S3: yearmon> <fctr> <dbl>
1 jan 1999 income 1
2 jun 1999 energy 3
3 jul 1999 energy 6
4 jul 1999 water 2
5 ago 1999 income 4
6 set 1999 energy 9
7 set 1999 income 7
8 nov 1999 water 5
9 dez 1999 water 8
Edit: the wide format:
reshape2::dcast(dfr, ym ~ type)
ym energy income water
1 jan 1999 NA 1 NA
2 jun 1999 3 NA NA
3 jul 1999 6 NA 2
4 ago 1999 NA 4 NA
5 set 1999 9 7 NA
6 nov 1999 NA NA 5
7 dez 1999 NA NA 8

Answer 3

If I understood your requirement correctly (from the description in the question), this is what you are looking for:
library(dplyr)
library(tidyr)
df %>% mutate(date = lubridate::month(date)) %>%
complete(household, date = 1:12) %>%
spread(type, value) %>% group_by(household, date) %>%
mutate(Total = sum(energy, income, water, na.rm = T)) %>%
select(household, Month = date, energy:water, Total)
#Source: local data frame [36 x 6]
#Groups: household, Month [36]
#
# household Month energy income water Total
# <fctr> <dbl> <dbl> <dbl> <dbl> <dbl>
#1 household1 1 NA NA NA 0
#2 household1 2 NA NA NA 0
#3 household1 3 NA NA 200 200
#4 household1 4 NA NA NA 0
#5 household1 5 NA NA NA 0
#6 household1 6 NA NA NA 0
#7 household1 7 NA NA NA 0
#8 household1 8 NA NA NA 0
#9 household1 9 300 NA NA 300
#10 household1 10 NA NA NA 0
# ... with 26 more rows
Note: I used the same df you provided in the question. The only change I made was the value column. Instead of 1:9, I used seq(100, 900, 100)
If I got it wrong, please let me know and I will delete my answer. I will add an explanation of what's going on if this is correct.