如何根据列之一中的值（日期）删除数据框中的行？

Question

I have a data frame that consists of daily data. It has 500,000+ rows and 18 columns . The 2nd column contains the date.

For example, it goes from 7/1/2017 to the current date, chronologically.

I pull the data every Monday and input it into R, but I only want data up until the most recent Friday.

I've set a variable equal to the most recent Friday's date (in the exact date format of the data):

library(lubridate)

LastFriday <- gsub("X", "", gsub("X0", "", format(
                                   Sys.Date() - wday(Sys.date()+1), "X%m/X%d/%Y))) 

which returns 9/15/2017

How do I delete all the rows in the data frame after the last row that contains last Friday's date?

Answer 1

The following should work, though I have not tested it

keep_index <- as.POSIXct(as.Date(df[,2]), "X%m/X%d/%Y") <= as.POSIXct(LastFriday, format = "X%m/X%d/%Y")
mydf <- df[keep_index, ]