# D Exercise 02

Last updated: 2020-09-28 17:50:13

## D.1 Question 1

• Run the following four expressions to load two vectors named year and co2 into memory
data(co2)
means = aggregate(co2, FUN = mean)
year = as.vector(time(means))
co2 = as.vector(means)
• The co2 vector contains $$CO_2$$ measurements in the atmosphere, in ppm units, during the period 1959-1997. The year vector contains the corresponding years.
• Calculate a vector of $$CO_2$$ differences between consecutive years, that is:
• $$CO_2$$ in 1960 minus $$CO_2$$ in 1959
• $$CO_2$$ in 1961 minus $$CO_2$$ in 1960
• and so on…
• Create a plot (Figure D.1) with lines and points showing the consecutive $$CO_2$$ differences as function of time (1960, 1961, etc.)
• The difference in $$CO_2$$ concentration between 2020 and 2019 was equal to 2.64. Add a point in red representing that difference to your plot (use a different point shape, such as pch=4).

(50 points)

## D.2 Question 2

• Read the rainfall.csv file into a data.frame object
• Find and print the station names where all nine months are with <10 mm of rainfall
## [1] "Yotveta" "Eilat"
• Note: you can define the vector m with month names in your code to subset the columns with monthly rainfall amounts, as shown in Section 4.4.3.
m = c("sep","oct","nov","dec","jan","feb","mar","apr","may")

(50 points)