Hello I tried to calculate a 5 Year Moving Average of Exchange Rate in R but I can’t get the code to work properly. I wanted to calculate a Moving Average similar to Atlas Conversion Factor used by World Bank for GNI estimates with some minor modifications.

Thanks,
Anon9001.

# Installing and loading required packages.
install.packages( “WDI”)
library(WDI)


# Getting GDP Deflator “NY.GDP.DEFL.ZS” and Exchange Rates “PA.NUS.ATLS”. 
WDI <- WDI(indicator=c("NY.GDP.DEFL.ZS","PA.NUS.ATLS"))

# Showing part of the Dataframe.
WDI |>

tibble()

                        country iso2c iso3c year NY.GDP.DEFL.ZS PA.NUS.ATLS
1                   Afghanistan    AF   AFG 1960             NA    45.00000
2                   Afghanistan    AF   AFG 1961             NA    45.00000
3                   Afghanistan    AF   AFG 1962             NA    45.00000
4                   Afghanistan    AF   AFG 1963             NA    45.00000
5                   Afghanistan    AF   AFG 1964             NA    45.00000
6                   Afghanistan    AF   AFG 1965             NA    45.00000
7                   Afghanistan    AF   AFG 1966             NA    45.00000
8                   Afghanistan    AF   AFG 1967             NA    45.00000
9                   Afghanistan    AF   AFG 1968             NA    45.00000
10                  Afghanistan    AF   AFG 1969             NA    45.00000
11                  Afghanistan    AF   AFG 1970             NA    45.00000
12                  Afghanistan    AF   AFG 1971             NA    45.00000
13                  Afghanistan    AF   AFG 1972             NA    45.00000
14                  Afghanistan    AF   AFG 1973             NA    45.00000
15                  Afghanistan    AF   AFG 1974             NA    45.00000


WDI |>

mutate (Atlas= median(PA.NUS.ATLS*(NY.GDP.DEFL.ZS/NY.GDP.DEFL.ZS/NY.GDP.DEFL.ZS[iso3c=="USA"]/NY.GDP.DEFL.ZS[iso3c=="USA"]),
                      
lag(PA.NUS.ATLS,n=1)*(NY.GDP.DEFL.ZS/lag(NY.GDP.DEFL.ZS,n=1)/NY.GDP.DEFL.ZS[iso3c=="USA"]/lag(NY.GDP.DEFL.ZS[iso3c=="USA"],n=1)), 

lag(PA.NUS.ATLS,n=2)*(NY.GDP.DEFL.ZS/lag(NY.GDP.DEFL.ZS,n=2)/NY.GDP.DEFL.ZS[iso3c=="USA"]/lag(NY.GDP.DEFL.ZS[iso3c=="USA"],n=2)), 

lag(PA.NUS.ATLS,n=3)*(NY.GDP.DEFL.ZS/lag(NY.GDP.DEFL.ZS,n=3)/NY.GDP.DEFL.ZS[iso3c=="USA"]/lag(NY.GDP.DEFL.ZS[iso3c=="USA"],n=3)), 

lag(PA.NUS.ATLS,n=4)*(NY.GDP.DEFL.ZS/lag(NY.GDP.DEFL.ZS,n=4)/NY.GDP.DEFL.ZS[iso3c=="USA"]/lag(NY.GDP.DEFL.ZS[iso3c=="USA"],n=4)) ,

lag(PA.NUS.ATLS,n=5)*(NY.GDP.DEFL.ZS/lag(NY.GDP.DEFL.ZS,n=5)/NY.GDP.DEFL.ZS[iso3c=="USA"]/lag(NY.GDP.DEFL.ZS[iso3c=="USA"],n=5)),na.rm=TRUE), by= c("country","year"))

The code above results in this error:

Error in `mutate()`:
ℹ In argument: `by = c("country", "year")`.
Caused by error:
! `by` must be size 17024 or 1, not 2.
Run `rlang::last_trace()` to see where the error occurred.