Converting Quarterly Data to Monthly Data and merging using R

Question

I am currently trying to figure out how to convert quarterly data to monthly data using R, since I want to merge my monthly return data with quarterly summary data.

What I currently have.

Quarterly Dataset

105  20080331 Y Y N N EQ  

Monthly Dataset

105  20080131 -0.087372  
105  20080229 -0.01609  
105  20080331 -0.022895  

What I want to achieve.

105  20080131 -0.087372 Y Y N N EQ  
105  20080229 -0.01609  Y Y N N EQ  
105  20080331 -0.022895 Y Y N N EQ  

I will have to run this for over 350000 separate rows, which I why I am seeking help. I am assuming the quarter values are the same as the former 3 months.

Update

Thanks for the quick and helpful response. However, I made a mistake in the formatting.

Y1 can take on 3 levels, namely "", "Y", "N".
Y2 can take on 3 levels, namely "", "Y", "N".
N1 can take on 4 levels, namely "", "B", "D", "E".
N2 can take on 3 levels, namely "", "F", "N".
V is return that can take on any level.

My data also ranges from January of 2008 to December of 2019. I believe this makes the problem a lot more complicated.

https://i.sstatic.net/MYE3w.png

https://i.sstatic.net/SQBY1.png

Answer 1

Create data:

quart_df <- 
  tibble::tribble(
    ~V1, ~V2, ~V3, ~V4, ~V5, ~V6, ~V7,
    105, "20080331", "Y", "Y", "N", "N", "EQ"
  )

month_df <- 
  tibble::tribble(
    ~V1, ~V2, ~V3,
    105,  20080131, -0.087372, 
    105,  20080229, -0.01609, 
    105,  20080331, -0.022895
  )

Join using dplyr::full_join():

library(dplyr)

full_join(month_df,
          select(quart_df, -V2),
          by = c("V1" = "V1"))
#> # A tibble: 3 x 8
#>      V1       V2    V3.x V3.y  V4    V5    V6    V7   
#>   <dbl>    <dbl>   <dbl> <chr> <chr> <chr> <chr> <chr>
#> 1   105 20080131 -0.0874 Y     Y     N     N     EQ   
#> 2   105 20080229 -0.0161 Y     Y     N     N     EQ   
#> 3   105 20080331 -0.0229 Y     Y     N     N     EQ

Answer 2

You can use merge:

Quarterly <- data.frame(Q=105, D=20080331, Y1="Y", Y2="Y", N1="N",  N2="N", E="EQ")

Monthly <- data.frame(Q = c(105,105,105),
                      D = c(20080131, 20080229, 20080331),
                      V = c(-0.087372,-0.01609, -0.022895))

merge(Monthly, Quarterly[,-2])

OR

merge(Monthly, Quarterly[,-which(names(Quarterly) == "D")])

Will output same result:

    Q        D         V Y1 Y2 N1 N2  E
1 105 20080131 -0.087372  Y  Y  N  N EQ
2 105 20080229 -0.016090  Y  Y  N  N EQ
3 105 20080331 -0.022895  Y  Y  N  N EQ

PS. For next time, please submit question in the reproductible format