使用 R 中数据框中的值创建一个列

Question

I have a dataset:

I want to create a column with the value from the date. In this example, it is 201201, but the excel may have a different date. So I do not want to create a date by writing 201201, rather than create a link between the column and date. The output should look like:

I appreciate any assistance you can provide me.

Answer 1

OK, so you have a data frame in R, similar to a worksheet in Excel. I'll just create one for demonstration purposes:

> data <- data.frame(Name=c("A","B","C"), books=c(3,5,8))
> data
  Name books
1    A     3
2    B     5
3    C     8

Now I will create a scalar of class "Date", similar to the value in your cell D1:

> Date <- as.Date("2001-12-20")
> Date
[1] "2001-12-20"

Now I will create a new column in data corresponding to this date:

> data$Date <- Date
> data
  Name books       Date
1    A     3 2001-12-20
2    B     5 2001-12-20
3    C     8 2001-12-20

Is that what you had in mind?

Edit : To import the date value from only cell D1 in an Excel file called "Report.xlsx" ( to automatize automaterize to make the process run with less human intervention):

> library(readxl)
> Report <- read_excel("E:/Book1.xlsx", range="D1", col_names="today", col_types = "text")
> Report %>% mutate(today=as.Date(today, format="%y%m%d"))