How to multiply specific values of a column with a specific value in R

Question

So I have a data frame with 2 columns. In the first column (year) I have data from multiple years. In the second column (wage_base) I have data regarding the base wage.

I want to multiply all the rows of the data frame belonging to the year 2010, for example, by the value of 1.2 and want to change the data frame permanently with these new values. I tried this so far:

dt$wage_base <- dt$wage_base * 1.2

I am just missing the part where I state that I only want to multiply 1.2 by the values of the year 2010.

Thank you for your help!

akrun · Accepted Answer · 2021-05-16 19:42:55Z

2

We can create a logical condition

i1 <- dt$year == 2010
dt$wage_base[i1] <- dt$wage_base[i1] * 1.2

Or with data.table

library(data.table)
setDT(dt)[, wage_base := as.numeric(wage_base)
   ][year == 2010, wage_base := wage_base * 1.2]

Or with dplyr

library(dplyr)
dt %>%
   mutate(wage_base = case_when(year == 2010 ~ wage_base * 1.2,
      TRUE ~ as.numeric(wage_base)))

answered May 16, 2021 at 19:42

akrun

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Onyambu · Accepted Answer · 2021-05-16 20:12:49Z

2

You could also do:

dt$wage_base <- dt$wage_base * 1.2^(dt$year == 2010)

answered May 16, 2021 at 20:12

Onyambu

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