--- 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) ```