2 Welcome

It’s a vast world out there. We’re going to cover a lot of ground. Don’t be scared. It’s going to be so. much. FUN!

I’m just playing right now and specifically thinking about code styling. So here’s a code chunk for producing a very basic plot.

# load the libraries
library(tidyverse)

# create a plot
ggplot(mpg, aes(displ, cty)) +
  geom_point() +
  geom_smooth() 

We could of course create some summary data too.

# create some summary data
mpg %>% 
  group_by(cyl) %>% 
  summarize(mean_cty = mean(cty),
            sd_cty = sd(cty))

## # A tibble: 4 x 3
##     cyl mean_cty sd_cty
##   <int>    <dbl>  <dbl>
## 1     4     21.0  3.50 
## 2     5     20.5  0.577
## 3     6     16.2  1.77 
## 4     8     12.6  1.81

But the above doesn’t give us an example of a string, which we’ll also use a lot, so let’s try an example with that.

mpg %>% 
  filter(manufacturer == "audi")

## # A tibble: 18 x 11
##    manufacturer model    displ  year   cyl trans   drv     cty   hwy fl    class
##    <chr>        <chr>    <dbl> <int> <int> <chr>   <chr> <int> <int> <chr> <chr>
##  1 audi         a4         1.8  1999     4 auto(l… f        18    29 p     comp…
##  2 audi         a4         1.8  1999     4 manual… f        21    29 p     comp…
##  3 audi         a4         2    2008     4 manual… f        20    31 p     comp…
##  4 audi         a4         2    2008     4 auto(a… f        21    30 p     comp…
##  5 audi         a4         2.8  1999     6 auto(l… f        16    26 p     comp…
##  6 audi         a4         2.8  1999     6 manual… f        18    26 p     comp…
##  7 audi         a4         3.1  2008     6 auto(a… f        18    27 p     comp…
##  8 audi         a4 quat…   1.8  1999     4 manual… 4        18    26 p     comp…
##  9 audi         a4 quat…   1.8  1999     4 auto(l… 4        16    25 p     comp…
## 10 audi         a4 quat…   2    2008     4 manual… 4        20    28 p     comp…
## 11 audi         a4 quat…   2    2008     4 auto(s… 4        19    27 p     comp…
## 12 audi         a4 quat…   2.8  1999     6 auto(l… 4        15    25 p     comp…
## 13 audi         a4 quat…   2.8  1999     6 manual… 4        17    25 p     comp…
## 14 audi         a4 quat…   3.1  2008     6 auto(s… 4        17    25 p     comp…
## 15 audi         a4 quat…   3.1  2008     6 manual… 4        15    25 p     comp…
## 16 audi         a6 quat…   2.8  1999     6 auto(l… 4        15    24 p     mids…
## 17 audi         a6 quat…   3.1  2008     6 auto(s… 4        17    25 p     mids…
## 18 audi         a6 quat…   4.2  2008     8 auto(s… 4        16    23 p     mids…

Finally, let’s write a quick function that has a logical in it (since we haven’t tested those yet).

mn <- function(x) {
  mean(x, na.rm = TRUE)
}
mn(mpg$hwy)

## [1] 23.44017

And overall, I’m pretty happy with how that’s all looking.