String to Date with leading X character - r

Question

I'm trying to convert the Date column to date format but I keep getting an error. I think the problem might be that the date is a character and has an X before the year:
HMC.Close Date
1 39.71 X2007.01.03
2 40.04 X2007.01.04
3 38.67 X2007.01.05
4 38.89 X2007.01.08
5 38.91 X2007.01.09
6 37.94 X2007.01.10
This is the code I've been running:
stock_honda <- expand.grid("HMC" = HMC$HMC.Close) %>%
"Date" = as.Date(row.names(as.data.frame(HMC))) %>%
subset(Date >"2021-02-28" & Date < "2022-03-11")
Error in charToDate(x) :
character string is not in a standard unambiguous format

Answer 1

You can use gsub to first remove the "X" that is causing a problem and then use ymd from lubridate package to convert the strings into Dates. Additionally, you can make that conversion using mutate(across(...)) from the dplyr package to do everything in a tidyverse-way.
library(dplyr)
library(lubridate)
df |>
# Mutate Date to remove X and convert it to Date
mutate(across(Date, function(x){
ymd(gsub("X","", x))
}))
# HMC.Close Date
#1 39.71 2007-01-03
#2 40.04 2007-01-04
#3 38.67 2007-01-05
#4 38.89 2007-01-08
#5 38.91 2007-01-09
#6 37.94 2007-01-10

Answer 2

Here is a pipeline that avoids prepending "X" to the dates in the first place:
library(quantmod)
getSymbols(c("FCAU.VI", "TYO", "VWAGY", "HMC"), na.rm = TRUE)
library(tidyverse)
stock_honda <- (HMC
%>% as.data.frame()
%>% rownames_to_column("Date")
%>% select(Date, HMC.Close)
%>% mutate(across(Date, lubridate::ymd))
%>% filter(between(Date, as.Date("2021-02-28"), as.Date("2022-03-11")))
)
It would be nice if there were a version of between that avoided the need to explicitly convert to dates. (filter("2021-02-28" < Date, Date < "2022-03-11") would also work for the last step.)