class: title-slide, right, top background-image: url(data:image/png;base64,#img/dawn.JPG) background-position: 90% 75%, 75% 75% background-size:cover .left-column[ # GRS Workshop<br>Introduction to ggplot ] .right-column[ ### First Steps in R **Eugene Hickey**<br> March 9th 2022 ] .palegrey[.left[.footnote[Graphic by [Elaine Hickey](https://photos.google.com/photo/AF1QipMjKNoaxyne8nte4HmxA6Th9-4fUfSbl_mx-_1G)]]] ??? Welcome to the workshop on ggplot. Where we'll show you how to create impressive data visualisations. --- class: center, inverse # Introduction to R Programming <br> <br> <br> ### R is case sensitive ---  --- <ol> <li> Using the Console <li> Storing Values <li> Fundamental Data Types <li> The Dataframe - Rows `\(\times\)` Columns <li> Dataframe Columns <li> Subsets of Dataframes <li> Small Useful Functions --- ## Using the Console - R is a calculator - can type, say, 45 + 17 and get the answer back - _\*_ is multiply, _/_ is divide - get constants like _pi_ for `\(\pi\)` - can run functions from the console like, say, _sqrt(x=49)_ (or just _sqrt(49)_) - can get help on these functions by typing, say, _?sqrt_ - to get list of help in the base package try _base::_ and then press _tab_ --- ## Storing Values - results of calculations can be stored - do this with _my_square_root_result <- sqrt(49)_ - the _<-_ reads as _gets_ (can also us equals sign, _=_, but that's sloppy) - keep board short cut for _<-_ is _alt_ and _-_ simultaneously - full list of RStudio shortcuts in _Help_ on the toolbar (ironically, of course, there is a keyboard shortcut for keyboard shortcuts help) - list of stored values given in the _Environment_ tab of RStudio --- ## Fundamental Data Types - _numeric_ (or _double_) is for numbers with decimals. Default for numbers. - _integer_ for counting numbers. Type in _x <- 72L_ to get integer 72 - _logical_ gives _TRUE_ and _FALSE_ - _character_ gives text. Try typing _x <- "I am Groot"_. Equivalent is _x <- 'I am Groot'_ - _complex_ is for stuff like _14 + 3i_. I've never used these. Ironically _sqrt(-1)_ gives an error rather than _i_ - _factor_. These deserve fuller explanation and get a slide of their own. --- ## Factors - super useful when only limited number of possible values for a variable - examples like _female_ / _male_ or _Alabama_ / _Alaska_ / .... _Wyoming_ - possible values are called _levels_ - levels have an order, default is alphabetical but can adjust this - _forcats_ package in the tidyverse deals with factors - have big impact on figures - figures will look different depending on whether a variable is a factor or a character - legend will be in the order of levels of a factor --- - can change between data types using the _as._ functions - e.g. _as.character()_, _as.numeric()_ - check out all the function in _forcats_ for dealing with factors - can figure out the data type using the _class()_ function --- ## Data Frames - these are the workhorse of R data types - look like spreadsheets - we'll work with them a lot - organised by _rows_ (across) and _columns_ (down) - each column must have the same type - can examine data frames using the _View()_ function (note, capital "V") - can find column names using the _names()_ function - related concepts are _tibbles_ and _data.tables_ --- ## Subsets of Data Frames - can access individual column elements by specifying the row and column position - e.g. _mtcars[2, 5]_ is the 2nd row of the fifth column - can access an entire row by leaving the column part blank - e.g. _mtcars[2, ]_ is the whole 2nd row - likewise get the entire column by leaving the row slot empty - e.g. _mtcars[,5]_ is the entire 5th column --- ## Subsets of Data Frames - can also access columns using _$_ - e.g. _mtcars$cyl_ gives the 2nd column, called _cyl_ - note _mtcars$cyl[2]_ gives the second element of this - can use a number range using _:_ to get a bunch of values - e.g. _mtcars[1:4, 2:4]_ takes a chunk of the mtcars data frame --- ## Some Useful Functions - _c()_ let's you create a vector of quantities. Coerced to same type - _is.na()_ let's you know if missing value, _sum(is.na())_ gives total of these - _dim()_ gives number of rows / columns in data frame - _summary()_, _str()_, _glimpse()_ show data frame parameters. Also _skim()_ from the _skimr_ package - I use _%in%_ quite a bit, checks if value is among a bunch of values - _"August" %in% month.name_ - _"£" %in% letters_ --- ## Some Useful Functions - _Sys.date_, _Sys.time_ - _ls()_ gives list of variables - _rm()_ gets rid of some variables - _file.list()_ gives list of files - _getwd()_ gives current location on disk, _setwd()_, or _Ctrl + H_, changes this - _sessionInfo()_ tells you what packages are loaded --- ## And Some Weird Characters - get to use a lot of the keyboard in R - we've seen _$_ to extract a column of a data frame - _()_ are arguments to functions - _[]_ are gateways to data frame elements - _ %>%_ is called the pipe and is really cool. _Ctrl + Shift + M_ shortcut - some logical operators: _!_ is NOT, _|_ is OR, _&_ is AND --- ## About Time We Did a Plot - type _Puromycin %>% ggplot(aes(x = conc, y = rate, color = state)) + geom_point()_ - hit _Ctrl + Shift + n_ to make a new R file - when you command at the console works, cut and paste it into this file --- ## About Time We Did a Plot - add some extra lines - type a _+_ at the end of the first line - add _geom_smooth(method = "loess", se = FALSE) +_ - add _scale_x_log10() +_ - add _theme_minimal() +_ - add _labs(title = "My First Plot", caption = "@Data_Vis_2020")_ <!-- --- --> <!-- ```{r first-plot, echo=FALSE} --> <!-- xaringanExtra::embed_xaringan(url = "https://eugene-hickey.shinyapps.io/01-colours/", ratio = "16:9") --> <!-- ``` --> --- <!-- -->