Subtracting a common xts object from all the columns of all xts objects of a list

Question

I have a list. List consists of 5 xts objects. Each object consists of 5 xts series. Each series consists of 183 observations. I want to extract one common series from all these series. The series I want to subtract is named risk_free. I have produced minimal example. In last line code produces error.

library(zoo)
library(xts)
library(PerformanceAnalytics)
managers_1 <- managers[,1:2]
manager_2 <- managers[,3:4]
list_managers <- list(managers_1,manager_2)
risk_free <- managers[,1]
## subtracting risk_free from all columns of all xts objects
list_managers_rf <- lapply(list_managers,"-",risk_free)

Answer 1

You get this error because xts objects always have a dim attribute (i.e. they're always a matrix). This differs from zoo, where dim will be dropped if the zoo object can be a vector.

So you can do this if you remove the dim attribute from risk_free before subtracting from the xts object with multiple columns. You can do that easily with drop().

list_managers_rf <- lapply(list_managers, "-", drop(risk_free))
lapply(list_managers_rf, tail, 2)
## [[1]]
##            HAM1    HAM2
## 2006-11-30    0  0.0089
## 2006-12-31    0 -0.0177
##
## [[2]]
##               HAM3   HAM4
## 2006-11-30  0.0152 0.0256
## 2006-12-31 -0.0005 0.0091