--- output: prettydoc::html_pretty: theme: architect highlight: vignette --- # R for Beginners: Examples of Simple Commands ## Problem 1 Use R as a calculator to compute the following values. (a) $9 + 3(6 - 4)$ {r} 9 + 3 * (6 - 4)  (b) $\sqrt{\frac{900}{12}}$ {r} sqrt(900 / 12)  (c) $ln(14^2)$, where $ln$ is the natural logarithm. {r} log(14^2)  (d) $e(1)$, which should give Euler's number. {r} exp(1)  (e) Calculate the absolute value of $13 - 22/1.2$ {r} abs(13 - 22 / 1.2)  ## Problem 2 Create the following vectors in R. (a) v1, which has the elements (5,7,3) {r} v1 <- c(5, 7, 3) v1  (b) v2, which has the elements (0,5,10,15,...,100) {r} v2 <- seq(0, 100, by = 5) v2  (c) v3, which has the elements (Yugoslavia,Yugoslavia,Canada,Canada,Czech Republic, Czech Republic,Croatia,Croatia,Hungary,Hungary,USA,USA) {r} v3 <- c("Yugoslavia", "Yugoslavia", "Canada", "Canada", "Czech Republic", "Czech Republic", "Croatia", "Croatia", "Hungary", "Hungary", "USA", "USA") v3  (d) v3.1, which is the same as v3 above but uses the repeat command. {r} v3.1 <- rep(c("Yugoslavia", "Canada", "Czech Republic", "Croatia", "Hungary", "USA"), each = 2) v3.1  (e) v4, which has the elements (2018,2012,2010,...,1918) {r} v4 <- c(2018, seq(2012, 1918, by = -2)) v4  (f) v5, a vector whose values start at 20, end at 0, and contains 36 evenly spaced elements {r} v5 <- seq(20, 0, length.out = 36) v5  ## Problem 3 For each of the following questions, use R to find the answer. (a) What are the 7th, 8th, and 12th elements of v5? {r} v5[c(7, 8, 12)]  (b) Which elements of v5 are less than or equal to 13.5? {r} which(v5 <= 13.5)  (c) What is the value of each of the elements of v5 that is less than or equal to 13.5? {r} v5[v5 <= 13.5]  (d) What is the percentage of elements of v5 that is less than 3.4? {r} mean(v5 < 3.4) * 100  (e) Which elements of v5 are greater than 10 *and* less than 13? {r} which(v5 > 10 & v5 < 13)  (f) What are the values of the elements of v5 that are greater than 10 and less than 13? {r} v5[v5 > 10 & v5 < 13]  ## Problem 4 Draw a pie chart with two slices - the values of v5 that are greater than, and those that are less than 15. In other words, your pie chart should show the relative percentage of values in v5 that are greater than 15 versus those that are less than 15. Bonus point: make one of the pie slices the color salmon and the other slice the color gold. {r} slices <- table(v5 > 15) lbls <- c("Less than 15", "Greater than 15") pie(slices, labels = lbls, col = c("salmon", "gold"))  ## Problem 5 Find the following for the vector v1 (which you created above): (a) mean {r} mean(v1)  (b) median {r} median(v1)  (c) range {r} range(v1)  (d) standard deviation {r} sd(v1)