--- title: "Midterm Exam" subtitle: "Computing in Molecular Biology 1" author: "WRITE YOUR NAME HERE" date: "2nd November 2016" output: html_document: self_contained: no --- At the course homepage you will find an *Rmarkdown* template. Please use it and send your answers by email to me. Change the name of the `.Rmd` file to your email address. Change "`@`" by "`.`" and avoid spaces. Example: if your email is "`name@gmail.com`" then the file should be "`name.gmail.com.Rmd`". Open the file on *Rstudio* and edit it. You should be able to **Knit HTML** and get the same results as this document. You may need to install `rmarkdown` using the *Install* button on the *Packages* window. **All answers are strictly personal. Any failure on doing so will be maximally penalized.** 1. **(10%)** Please answer the following questions: + Why we study computing in molecular biology? > REPLACE THIS TEXT WITH YOUR ANSWER + What is a *computer*? what are computers useful for? > REPLACE THIS TEXT WITH YOUR ANSWER + What are the parts of a computer? > REPLACE THIS TEXT WITH YOUR ANSWER + How do computers represent information? > REPLACE THIS TEXT WITH YOUR ANSWER + What is a *prompt*? What is the interpretation? > REPLACE THIS TEXT WITH YOUR ANSWER 2. **(10%)** Please answer the following questions: + What is the *natural way* to represent text in a computer? Can you use *Microsoft Word* for scientific computing? > REPLACE THIS TEXT WITH YOUR ANSWER + What are the advantages of *Markdown* as a way to represent documents? > REPLACE THIS TEXT WITH YOUR ANSWER 3. **(10%)** Please answer the following questions: + What are the units to measure the size of data in the computer memory? > REPLACE THIS TEXT WITH YOUR ANSWER + How much memory do you need to store a 12 megapixels picture, not compressed and greyscale > REPLACE THIS TEXT WITH YOUR ANSWER + How much memory do you need to store 10 minutes of low quality audio sampled 8000 times per second with 8 bits per sample? > REPLACE THIS TEXT WITH YOUR ANSWER + How much memory do you need to store 10 minutes of high quality **stereo** audio sampled 44100 times per second with 16 bits per sample? > REPLACE THIS TEXT WITH YOUR ANSWER 4. **(10%)** Please answer the following questions: + Which are the basic *data types in R*? > REPLACE THIS TEXT WITH YOUR ANSWER + What is the meaning of `NA`? Why it is useful? > REPLACE THIS TEXT WITH YOUR ANSWER + What types of data can be used as indices of vectors in R? What are the advantages of each one? > REPLACE THIS TEXT WITH YOUR ANSWER 5. **(15%)** Please answer the following questions: + What is the difference between a *vector* and a *matrix* in R? > REPLACE THIS TEXT WITH YOUR ANSWER + What is the difference between a *vector* and a *list* in R? > REPLACE THIS TEXT WITH YOUR ANSWER + What is the difference between a *list* and a *data frame* in R? > REPLACE THIS TEXT WITH YOUR ANSWER + What is the difference between a *matrix* and *data frame* in R? > REPLACE THIS TEXT WITH YOUR ANSWER 6. **(15%)** Write R commands to produce this output ```{r q6a} # replace this line with your code ``` ```{r q6b} # replace this line with your code ``` ```{r q6c} # replace this line with your code ``` ```{r q6d} # replace this line with your code ``` ```{r q6e} # replace this line with your code ``` 7. **(15%)** Write an R command to create the variable `x` with this content: ```{r q7a} # complete this code x <- list() x ``` Using the same variable `x`, write the commands to produce this output ```{r q7b} # replace this line with your code ``` ```{r q7c} # replace this line with your code ``` ```{r q7d} # replace this line with your code ``` 8. **(15%)** Your computer has already a `longley` data frame with some macroeconomic values. Write an R command to get the values for the 3rd row ```{r q8a} # replace this line with your code ``` Write an R command to get the values of GNP ```{r q8b} # replace this line with your code ``` Write an R command to get the ywars where `Armed.Forces` was over 300 ```{r q8c} # replace this line with your code ```