Is there a way to mutate a new column that combines an integer column with a character column

Question

Here is a section of my full dataset:

 PlotNumber      Date
1       2011 7.13.2020
2       2021 7.13.2020
3       2031 7.13.2020
4       2011 7.14.2020
5       2021 7.14.2020
6       2031 7.14.2020

I would like to create a new column that takes the number from "PlotNumber" and adds another number to the end based on which character is in the "Date" column. Below is an example of what I would like the final dataset to look like.

 PlotNumber      Date      Plot
1       2011 7.13.2020 20111
2       2021 7.13.2020 20211
3       2031 7.13.2020 20311
4       2011 7.14.2020 20112
5       2021 7.14.2020 20212
6       2031 7.14.2020 20312

My thought process is to use the mutate function from dplyr to do this, but I don't know how to assign an identifying number to the character in the "Date" column. I used the search function on StackOverflow but was not able to find anything to accomplish this specific task.

Any help would be greatly appreciated. Thanks in advance.

Answer 1

Here is an option - get the sequence based on 'PlotNumber' (rowid from data.table or use group_by(PlotNumber) and then use row_number())

library(dplyr)
library(stringr)
library(data.table)
df1 %>%
   mutate(Plot = str_c(PlotNumber, rowid(PlotNumber)))

-output

   PlotNumber      Date  Plot
1       2011 7.13.2020 20111
2       2021 7.13.2020 20211
3       2031 7.13.2020 20311
4       2011 7.14.2020 20112
5       2021 7.14.2020 20212
6       2031 7.14.2020 20312

---

Or with dplyr alone

df1 %>%
    group_by(PlotNumber) %>%
    mutate(Plot = str_c(PlotNumber, row_number())) %>%
    ungroup

---

Or with base R

df1$Plot <- with(df1, paste0(PlotNumber, ave(seq_along(PlotNumber), 
       PlotNumber, FUN = seq_along))

data

df1 <- structure(list(PlotNumber = c(2011L, 2021L, 2031L, 2011L, 2021L, 
2031L), Date = c("7.13.2020", "7.13.2020", "7.13.2020", "7.14.2020", 
"7.14.2020", "7.14.2020")), class = "data.frame", 
row.names = c("1", 
"2", "3", "4", "5", "6"))