Problem with "ifelse" - Object cannot be coerced to type 'double

Question

Good afternoon. I’ve been researching the error, but I haven’t found a solution.

I tried to transform the object a but I was unsuccessful.

Any hint?

I have the following problem:

class(ativos)
[1] "xts" "zoo"

model_list <- lapply(ativos, function(x)
lm(BBAS3 ~ x, data = ativos))

resid_list <- lapply(model_list, residuals)
lapply(resid_list, summary)

f <- function(residuals){
  z <- (residuals - mean(residuals))/sd(residuals)
  return(z)}
a <- lapply(resid_list, f)

a_if <- ifelse(a <= -2,
               "Z",
               "N")

Error in ifelse(a <= -2, "Z", "N") : 
(list) object cannot be coerced to type 'double'

Thank you.

EDIT: Sorry for the lack of information.

dput(head(ativos, 5))

structure(c(66124.53, 66967.64, 66712.88, 67975.58, 67814.24, 
17.14, 17.25, 17.38, 18.02, 17.97, 31.18, 31.38, 31.48, 31.86, 
32.89, 26.12, 26.07, 25.87, 26.36, 26.31, 26.86, 26.93, 26.77, 
27.35, 27.26, 27.57, 28.53, 28.16, 28.85, 29.5, 21.8, 23.47, 
22.96, 22.82, 22.61, 43.2, 42.77, 43.2, 43.96, 43.9, 33.95, 33.95, 
33.89, 32.82, 33.14, 13.32, 13.13, 13.03, 13.39, 13.22, 13.16, 
13.05, 13, 13.1, 12.91, 17.28, 17.95, 18.1, 18.3, 18.45, 23.02, 
23.33, 23.12, 23.97, 24.23, 8.66, 8.92, 8.98, 9.61, 9.9, 32.57, 
33.27, 32.35, 33.43, 34.86, 41.95, 41.62, 42.12, 42.55, 42.4, 
27.11, 27.75, 27.34, 28.1, 27.9, 14.14, 13.86, 13.67, 13.67, 
13.41, 0, 0, 0, 0, 0, 9.16, 9.28, 9.35, 9.42, 9.49, 29.72, 29.86, 
29.43, 29.89, 29.72, 22.63, 22.86, 22.17, 22.32, 22.15, 26.7, 
26.75, 25.75, 25.71, 25.32, 18.12, 18.35, 18.31, 18.34, 18.1, 
13.89, 13.85, 13.71, 13.95, 13.92, 57.19, 57.39, 57.5, 58, 59.58, 
14.7, 14.85, 15.02, 15, 14.85, 20.37, 20.88, 20.88, 20.69, 20.64, 
12.89, 13.3, 13.14, 13.36, 13.46, 5.65, 5.71, 5.65, 5.83, 5.96, 
6.95, 7.11, 7.32, 7.8, 8.22, 28.59, 28.8, 28.46, 29.04, 27.8, 
30.95, 31.54, 31.3, 31.68, 31.2, 0, 0, 0, 0, 0, 8.84, 8.82, 8.78, 
9.12, 9.09, 23.43, 23.17, 23.11, 23.92, 23.65, 12.06, 12.15, 
12.01, 12.2, 12.18, 15.29, 15.28, 15.56, 16.06, 15.8, 13.08, 
13.1, 13.36, 13.6, 13.55, 17, 17, 16.8, 16.2, 16.3, 22.47, 22.57, 
23.09, 23.54, 23.54, 17.29, 19, 18.69, 19.25, 19.5, 7.2, 7.38, 
7.34, 7.35, 7.22, 14, 13.72, 13.72, 13.83, 13.9, 22.42, 22.42, 
22.23, 22.39, 22, 26.56, 26.94, 26.68, 27.17, 26.82, 57.91, 57.53, 
57.39, 58.91, 58.45, 16.35, 16.56, 16.81, 16.86, 16.97, 15.58, 
15.62, 15.82, 15.84, 15.86, 19.9, 20.55, 20.18, 20.1, 19.95, 
64, 63.24, 63.57, 65.99, 64.65, 8.34, 8.7, 8.55, 8.74, 8.8, 12.35, 
12.35, 12.86, 12.93, 12.62, 34.49, 35.56, 34.25, 35.7, 34.89, 
32.86, 33.99, 33.3, 34.38, 33.76, 53.1, 54.7, 54.32, 56.38, 59.25, 
20.56, 20.14, 19.7, 20, 20.39, 21.3, 21.86, 21.45, 21.54, 21.83, 
9.68, 9.6, 9.69, 9.94, 9.82, 67.01, 67, 66.6, 68.81, 68.69, 5.37, 
5.44, 5.45, 5.52, 5.46, 32.8, 35.81, 34.4, 33.82, 33.77, 47.6, 
47.5, 46.95, 47.28, 46.7, 3.71, 3.75, 3.7, 3.62, 3.65, 0, 0, 
0, 0, 0, 12.55, 12.65, 12.61, 13.09, 12.88), class = c("xts", 
"zoo"), .indexCLASS = "Date", tclass = "Date", .indexTZ = "UTC", tzone = "UTC", index = structure(c(1486684800, 
1486944000, 1487030400, 1487116800, 1487203200), tzone = "UTC", tclass = "Date"), .Dim = c(5L, 
66L), .Dimnames = list(NULL, c("IBOV", "ABEV3", "BBAS3", "BBDC3", 
"BBDC4", "BBSE3", "BRAP4", "BRFS3", "BRKM5", "BRML3", "BTOW3", 
"CCRO3", "CIEL3", "CMIG4", "CPLE6", "CSAN3", "CVCB3", "CYRE3", 
"DOLFUT", "ECOR3", "EGIE3", "ELET3", "ELET6", "EMBR3", "ENBR3", 
"EQTL3", "ESTC3", "FLRY3", "GGBR4", "GOAU4", "GOLL4", "HYPE3", 
"IGTA3", "INDFUT", "ITSA4", "ITUB3", "JBSS3", "KLBN11", "KROT3", 
"LAME4", "LREN3", "MGLU3", "MRFG3", "MRVE3", "MULT3", "NATU3", 
"PCAR4", "PETR3", "PETR4", "QUAL3", "RADL3", "RAIL3", "RENT3", 
"SANB11", "SBSP3", "SMLS3", "SUZB3", "TAEE11", "TIMP3", "UGPA3", 
"USIM5", "VALE3", "VIVT4", "VVAR3", "WDOFUT", "WEGE3")))```

Answer 1

The object a is class "list" because it is the result of lapply of the previous instruction. So just apply lapply once again.

a_if <- lapply(a, function(.a) ifelse(.a <= -2, "Z", "N"))

If you want to have a form other than a list, see, for example, sapply.

a_if2 <- sapply(a, function(.a) ifelse(.a <= -2, "Z", "N"))
class(a_if2)
#[1] "matrix"