10.3 Add Columns
20200814 Adding columns to a dataset is accomplished with dplyr::mutate(). Within a pipeline dplyr::mutate() will modify the data as it passes through.
In the example below we add two new columns to the dataset. A tee pipe is used to print a sample of the resulting dataset using dplyr::select() and dplyr::sample_frac() within the curly braces. The ongoing pipe assigns the result into a new variable.
ds %>%
mutate(range_temp=max_temp-min_temp,
describe_temp=case_when(max_temp > 30 ~ "hot",
max_temp > 20 ~ "mild",
max_temp > 0 ~ "cold",
TRUE ~ "freezing")) %T>%
{
select(., date, location, ends_with("_temp")) %>%
sample_frac() %>%
print()
} ->
newds## # A tibble: 275,410 × 6
## date location min_temp max_temp range_temp describe_temp
## <date> <chr> <dbl> <dbl> <dbl> <chr>
## 1 2020-06-13 Albury 3.6 16.4 12.8 cold
## 2 2023-02-24 Katherine NA NA NA freezing
## 3 2019-01-30 Adelaide 17.3 40.2 22.9 hot
## 4 2018-12-26 Perth 16.8 28.2 11.4 mild
## 5 2020-02-22 Canberra 13.9 26.3 12.4 mild
## 6 2010-06-17 CoffsHarbour 10.1 19 8.9 cold
## 7 2023-01-19 NorahHead 20.1 21.1 1 mild
## 8 2025-09-13 Albury 3.1 18.8 15.7 cold
## 9 2026-01-24 WaggaWagga 17.8 37.8 20 hot
## 10 2011-09-29 WaggaWagga 10 13.7 3.7 cold
## # ℹ 275,400 more rowsTo overwrite the original dataset instead of saving it as a new dataset, replace the first pipe with an assignment pipe magrittr::%<>%.
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