How to treat residuals() output as xts object.

> residuals(lm(apply.quarterly(SP5[k2k],mean)[,1] ~ PAq[k2k] * UCq[k2k] * G[k2k]*CSq[k2k] - UCq[k2k] -G[k2k] - PAq[k2k]*G[k2k] - UCq[k2k]*G[k2k]*CSq[k2k]))

above outpus like

2000-03-01   2000-06-01   2000-09-01   2000-12-01   2001-03-01   2001-06-01   2001-09-01
-18.6280839  120.6122215  186.8549495  162.9236931   63.9004346  -15.8557805  -34.5815455
2001-12-01   2002-03-01   2002-06-01   2002-09-01   2002-12-01   2003-03-01   2003-06-01 (....)

and class are like,

> class(residuals(lm(apply.quarterly(SP5[k2k],mean)[,1] ~ PAq[k2k] * UCq[k2k] * G[k2k]*CSq[k2k] - UCq[k2k] -G[k2k] - PAq[k2k]*G[k2k] - UCq[k2k]*G[k2k]*CSq[k2k])))
[1] "xts" "zoo"

however, this is not able to be treated as usual xts object. then do as below.

> resi <- residuals(lm(apply.quarterly(SP5[k2k],mean)[,1] ~ PAq[k2k] * UCq[k2k] * G[k2k]*CSq[k2k] - UCq[k2k] -G[k2k] - PAq[k2k]*G[k2k] - UCq[k2k]*G[k2k]*CSq[k2k]))
> resi[,1]
                   [,1]
2000-03-01  -18.6280839
2000-06-01  120.6122215
2000-09-01  186.8549495
2000-12-01  162.9236931
2001-03-01   63.9004346
(....)

> class(resi[,1])
[1] "xts" "zoo"
>plot(resi[,1])