How to combine multiple dataframe by MonthYear in R

Question

I have below mentioned different dataframe:

DF1:

Origination_Date        Count1        Count2
2018-07-01              147           205
2018-07-05              180           345
2018-07-08              195           247
2018-08-04              205           788

DF2:

Date              ID
2018-07-01        I-1
2018-07-02        I-2
2018-07-02        I-3
2018-07-03        I-4
2018-07-03        I-5
2018-08-04        I-6
2018-08-04        I-7

DF3

Create_Date           ID
2018-07-01            I-1
2018-07-02            I-2
2018-07-03            I-3
2018-08-04            I-4
2018-08-04            I-5

By utilizing the above multiple dataframe, I want to create a new dataframe group by MonthYear and represent consolidated count on month wise and date wise as shown in the below sample dataframe.

Required Output:

Month   Count1   Count2   DF2_Count(ID)    DF3_Count(ID)
Aug-18  205      788      2                2
Jul-18  522      797      5                3
Jun-18  0        0        0                0

The above mentioned same data structure want to create on date basis as well, I have tried using group_by function and could create the required dataframe for each separate datafreme but not by consolidated all the dataframe.

Note: - Though I don't have Jun-18 month in my datframe, I want to create a row for the same month (want to create atleast three month in the required output dataframe considering the latest month (i.e if its Sep-18 than Aug-18 and Jul-18). - If any dataframe has 0 row than show count 0 is Required Output.

Answer 1

What about something like this:

# your data
df1 <- data.frame (Origination_Date = c('2018-07-01','2018-07-05','2018-07-08','2018-08-04'),
                   Count1 = c(147,180,195,205), Count2 = c(205,345,247,788))
df2 <- data.frame (Date = c('2018-07-01','2018-07-02','2018-07-02','2018-07-03','2018-07-03','2018-08-04','2018-08-04'),
                   ID = c('I-1','I-2','I-3','I-4','I-5','I-6','I-7'))
df3 <- data.frame (Create_Date = c('2018-07-01','2018-07-02','2018-07-03','2018-08-04','2018-08-04'), ID = c('I-1','I-2','I-3','I-4','I-5'))

# package to manage date
library(lubridate)

# first we create the yyyy-mm data.frame grouped
df1_1 <- df1 %>% 
       mutate(ym = format(ymd(Origination_Date),'%Y-%b')) %>%
       group_by(ym) %>%
       summarise(Count1 = sum(Count1) ,Count2 = sum(Count2))

df2_1 <- df2 %>%
      mutate(ym = format(ymd(Date),'%Y-%b')) %>%
      group_by(ym) %>%
      summarise(DF2_Count = n())

df3_1 <- df3 %>%
        mutate(ym = format(ymd(Create_Date),'%Y-%b')) %>%
        group_by(ym) %>%
       summarise(DF3_Count = n())


# join them together
df_1 <- df1_1 %>% full_join(df2_1, by = 'ym') %>% full_join(df3_1, by = 'ym')

    > df_1
# A tibble: 2 x 5
  ym       Count1 Count2 DF2_Count DF3_Count
  <chr>     <dbl>  <dbl>     <int>     <int>
1 2018-Aug    205    788         2         2
2 2018-Jul    522    797         5         3

Now the tricky part, add the missing month, I've created a pair of if whom checks if there is not the max month-year - 2 (the second), it add a fake row, and the first for the last but one.

if(
  format(floor_date(as.Date(max(union(union(df1[,1], df2[,1]),df3[,1]))), "month") - months(1),'%Y-%b') %in% df_1$ym == F){
  df_2 <- data.frame(ym =format(floor_date(as.Date(max(union(union(df1[,1], df2[,1]),df3[,1]))), "month") - months(1),'%Y-%b'),
                     Count1 = 0,
                     Count2 = 0,
                     DF2_Count= 0,
                     DF3_Count= 0)
  rbind(df_1,df_2)} else {'it already exists'}
[1] "it already exists"


if(
format(floor_date(as.Date(max(union(union(df1[,1], df2[,1]),df3[,1]))), "month") - months(2),'%Y-%b') %in% df_1$ym == F){
df_2 <- data.frame(ym =format(floor_date(as.Date(max(union(union(df1[,1], df2[,1]),df3[,1]))), "month") - months(2),'%Y-%b'),
                   Count1 = 0,
                   Count2 = 0,
                   DF2_Count= 0,
                   DF3_Count= 0)
rbind(df_1,df_2)
} else {'it already exists'}

    # A tibble: 3 x 5
      ym       Count1 Count2 DF2_Count DF3_Count
      <chr>     <dbl>  <dbl>     <dbl>     <dbl>
    1 2018-Aug    205    788         2         2
    2 2018-Jul    522    797         5         3
    3 2018-Jun      0      0         0         0