Dictionary.Rmd

---
title: "Dictionary"
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---

```{r setup, include=FALSE}
knitr::opts_chunk$set(message=FALSE,warning=FALSE, cache=TRUE)
```

### List of functions
General bits

1.	help(topic) – search r studio for tips on a function for topic by clicking “Help” on the bottom right panel and performing a search under “Topic”; similar to “?topic”.
2.	?topic - search r studio for tips on a function for topic by typing “?[insert topic name here]” in the Console; similar to “help(topic)”.
3.	ls() – shows a list of characters used by the user.
4.	dir() – shows a list of files; see list.files().
5.	list.files() – shows a list of files; dir().
Input and output
1.	save() – saves a data.
2.	load() – loads data that was previously saved using “save()”.
3.	data() – loads data.
4.	library() – downloads packages unto r studio.
5.	read.table() – turns data from a file into a table.
6.	read.csv() – turns data from a csv into a table.
7.	scan() – turns data from a file into a list.
8.	print() – returns argument.
9.	cat() – turns data into a string and concatenates them, before returning them to the argument.
10.	write.table() – turns data into a matrix before returning it to argument and turning it into a file.
Data Creation
1.	c() – concatenates variables into a vector.
2.	from:to (where from and to are replaced with numbers, e.g. 1:10) – to include numbers “from” to “to” (e.g. to include numbers 1 to 10).
3.	seq() – a sequence of number “from” one number “to” another.
4.	rep() – repeats a value.
5.	data.frame() – a matrix
6.	list() – holds list of variables.
7.	matrix() – a dataframe.
8.	factor() – categorizes a vector as a factor.
9.	rbind() – concatenates vectors into a row in a dataframe.
10.	cbind() – concatenates vectors into column in a dataframe.

```{r}

```
### Slicing and extracting data
Indexing vectors

1.	x[n] nth element
2.	x[-n] all but nth element
3.	x[1:n] first n elements
4.	x[-(1:n)] elements from n+1 to the end
5.	x[c(1,4,2)] specific elements
6.	x[“name”] elements named “name”
7.	x[x>3] all elements greater than 3
8.	x[x > 3 & x < 5] all elements between 3 and 5
9.	x[x %in% c(“a”,“and”,“the”)] all elements in given set
```{r}

```
### Indexing lists
1.	x[n] list with elements n
2.	x[[n]] nt h element of the list
3.	x[[“name”]] element of the list named “name”
4.	x$name id.
```{r}

```
### Indexing matrices
1.	x[i,j] element at row i, column j
2.	x[i,] row i
3.	x[,j] column j
4.	x[,c(1,3)] columns 1 and 3
5.	x[“name”,] row named “name”
```{r}

```
### Indexing data frames (matrix indexing plus the following)
1.	x[[“name”]] column named “name”
2.	x$nameid.
```{r}

```
### Variable conversion
1.	as.data.frame(x)
2.	as.numeric(x)
3.	as.logical(x)
4.	as.character(x)
```{r}

```
### Variable information
1.	is.na(x)
2.	is.null(x)
3.	is.data.frame(x)
4.	is.numeric(x)
5.	is.character(x)
6.	length(x)
7.	dim(x)
8.	dimnames(x)
9.	nrow(x)
10.	ncol(x)
11.	class()
12.	attributes()

```{r}

```
### Data selection and manipulation
1.	which.max()
2.	which.min()
3.	which()
4.	sort()
5.	unique()
6.	table()
7.	sample()

```{r}

```
### Math
1.	max()
2.	min()
3.	range()
4.	sum()
5.	mean()
6.	median()
7.	var()
8.	sd()
9.	cor()
10.	round()
11.	abs()

```{r}

```
### Matrices
1.	t()
2.	diag()
3.	rowSums()
4.	colSums()
5.	rowMeans()
6.	colMeans()

```{r}

```
### Advanced Data processing
1.	apply()
2.	aggregate()

```{r}

```
### Strings
1.	paste()
2.	strsplit()
3.	tolower()
4.	toupper

```{r}

```
### Plotting
1.	hist()
2.	plot()

```{r}

```
### Distributions
1.	rnorm()
2.	runif()

```{r}

```
### Programming
1.	show that you can define a function
2.	show that you can write a for loop
3.	show that you can write a while loop
4.	show that you can write an if else statement
5.	Explain what return() does inside a function, show you can use it
6.	Explain what break() does, show you can use it

```{r}

```
### Installing some packages
Use the packages tab in R-studio to install these packages. You will need to be connected to the internet when you do this. If you are installing on your laptop, or on R-studio Cloud, then these packages will not need to installed again.
1.	ggplot2
2.	dplyr
3.	shiny
4.	data.table
5.	reshape2
6.	stringr