Number epochs in geological periods
Exercise Type: Implementation
Instructions
Calculate the number of series/epochs in all Phanerozoic geological systems/periods! Here are the steps that need to be taken:
-
Download this file: stages.csv
-
Read it into R with
read.csv()
! -
Subset to the Phanerozoic!
-
Select one system/period, e.g. the
"Jurassic"
, and subset the result of step 3. to the corresponding part. Count how many different series/epochs there was in it. (length(unique())
) -
Get the names of every system/period, and have these in a vector, where every item occurs only once (character vector).
-
Repeat step 4 with a
for()
loop, calculate the number of epochs in every period. -
Assign names to the values.
+1. Use the combination of column subsetting, unique()
and table()
to get the same result (steps 4-7) without writing a loop.
Expected output
A named numeric vector:
- names: periods/systems
- values: the number of series/epochs in every period.