如何从日期中删除日期并仅从 r markdown 的大型数据集中的列中保留月份和年份？

Question

I have a large dataset and one of the columns includes dates formatted DD/MM/YYYY and I would like to just have MM/YYYY. Is there a way to apply this to the entire column in the dataset dat$date ?

Answer 1

We can convert to Date class first with as.Date and then use format

dat$date <- format(as.Date(dat$date, "%d/%m/%Y"), "%m/%Y")

Or another option is regex to match the digits ( \\d+ ) from the start ( ^ ) of the string followed by / and replace with blank ( '' )

dat$date <- sub("^\\d+\\/", "", dat$date)

data

dat <- data.frame(date = c('05/10/2015', '15/05/2010'), stringsAsFactors = FALSE)