Description

I could not use addEventLines having both xts' indexed with yearmon format

Expected behavior

same as with YYYY-MM-DD indexes

Minimal, reproducible example

require(magrittr)
require(xts)
require(ecb)

data.frame(
  begin = c("1998-10-01","2000-04-01","2001-10-01","2008-10-01","2009-10-01","2020-04-01"),
  events = c("LTCM","dot com bubble","9/11","Lehman Bros.","Eurozone Crisis","Pandemic")) %>%
  read.zoo(FUN=as.yearmon) %>%
  as.xts() -> historical

'ICP.M.U2.N.000000.4.ANR' %>% ecb::get_data() %>%
  .[c('obstime','obsvalue')] %>%
  read.zoo(FUN=as.yearmon) %>% as.xts() -> HICP

plot(HICP,
     col='navy',lty=1,lwd=1.5, cex=0.5,
     grid.ticks.lty="dotted")
addEventLines(historical, col="#3357FF", cex=1,lty=1.5,lwd=2, srt=90, pos=2,offset=-.6,on=0)

Session Info

R version 4.0.5 (2021-03-31)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Debian GNU/Linux 10 (buster)

Matrix products: default
BLAS: /usr/lib/x86_64-linux-gnu/openblas/libblas.so.3
LAPACK: /usr/lib/x86_64-linux-gnu/libopenblasp-r0.3.5.so

locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 LC_MONETARY=en_US.UTF-8
[6] LC_MESSAGES=en_US.UTF-8 LC_PAPER=en_US.UTF-8 LC_NAME=C LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] stats graphics grDevices datasets utils methods base

other attached packages:
[1] magrittr_2.0.1 ecb_0.4.0 xts_0.12.1 zoo_1.8-9

loaded via a namespace (and not attached):
[1] Rcpp_1.0.6 lattice_0.20-44 XML_3.99-0.6 rsvg_2.1.2 digest_0.6.27 plyr_1.8.6 R6_2.5.0 grid_4.0.5
[9] rsdmx_0.6 evaluate_0.14 httr_1.4.2 quantmod_0.4.18 rlang_0.4.11 cachem_1.0.4 renv_0.13.2 curl_4.3.1
[17] TTR_0.24.2 rmarkdown_2.8 tools_4.0.5 xfun_0.22 yaml_2.2.1 fastmap_1.1.0 compiler_4.0.5 htmltools_0.5.1.1
[25] memoise_2.0.0 knitr_1.33