new link-checker; fix links

README.md

@@ -3,7 +3,7 @@
 
 # Exercise Solutions to R for Data Science
 
-This repository contains the code and text behind the [Solutions for R for Data Science](https://jrnold.github.io/r4ds-exercise-solutions/), which, as its name suggests, has solutions to the the exercises in [R for Data Science](http://r4ds.had.co.nz/) by Garrett Grolemund and Hadley Wickham.
+This repository contains the code and text behind the [Solutions for R for Data Science](https://jrnold.github.io/r4ds-exercise-solutions/), which, as its name suggests, has solutions to the the exercises in [R for Data Science](https://r4ds.had.co.nz/) by Garrett Grolemund and Hadley Wickham.
 
 The R packages used in this book can be installed via
 ```r

_common.R

@@ -26,12 +26,12 @@ SOURCE_URL <- stringr::str_c("https:/", "github.com", "jrnold",
   "r4ds-exercise-solutions",
   sep = "/"
 )
-PUB_URL <- stringr::str_c("http:/", "jrnold.github.io",
+PUB_URL <- stringr::str_c("https:/", "jrnold.github.io",
   "r4ds-exercise-solutions",
   sep = "/"
 )
 
-R4DS_URL <- "http://r4ds.had.co.nz"
+R4DS_URL <- "https://r4ds.had.co.nz"
 
 r4ds_url <- function(...) {
   stringr::str_c(R4DS_URL, ..., sep = "/")

_config.yml

@@ -1,5 +1,5 @@
 github_repo: "jrnold/r4ds-exercise-solutions"
-deploy_url: "https://jrnold.github.io/r4ds-exercise-solutions"
+deploy_url: "https://jrnold.github.io/r4ds-exercise-solutions/"
 r4ds:
   github_repo: "hadley/r4ds"
   url: "https://r4ds.had.co.nz"

functions.Rmd

@@ -154,7 +154,7 @@ coef_variation(c(1:5, NA), na.rm = TRUE)
 
 <div class="question">
 
-Follow <http://nicercode.github.io/intro/writing-functions.html> to write your own functions to compute the variance and skew of a numeric vector.
+Follow <https://nicercode.github.io/intro/writing-functions.html> to write your own functions to compute the variance and skew of a numeric vector.
 
 </div>
 
@@ -697,7 +697,7 @@ Why doesn’t this currently work? How could you fix it?
 
 <div class="answer">
 
-This is the definition of the rule function from the [chapter](http://r4ds.had.co.nz/functions.html).
+This is the definition of the rule function from the [chapter](https://r4ds.had.co.nz/functions.html).
 ```{r}
 rule <- function(..., pad = "-") {
   title <- paste0(...)

import.Rmd

@@ -290,7 +290,7 @@ The list in the documentation for `stringi::stri_enc_detect()` is a good list of
 For more information on character encodings see the following sources.
 
 -   The Wikipedia page [Character encoding](https://en.wikipedia.org/wiki/Character_encoding), has a good list of encodings.
--   Unicode [CLDR](http://cldr.unicode.org/) project
+-   Unicode [CLDR](https://cldr.unicode.org/) project
 -   [What is the most common encoding of each language](https://stackoverflow.com/questions/8509339/what-is-the-most-common-encoding-of-each-language) (Stack Overflow)
 -   "What Every Programmer Absolutely, Positively Needs To Know About Encodings And Character Sets To Work With Text", <http://kunststube.net/encoding/>.
 

index.Rmd

@@ -27,9 +27,9 @@ knitr::opts_chunk$set(cache = FALSE)
 
 <img src="./img/r4ds-exercise-solutions-cover.png" width="250" height="375" alt="Cover image" align="right" style="margin: 0 1em 0 1em"/>
 
-This book contains the **exercise solutions** for the book [*R for Data Science*](http://amzn.to/2aHLAQ1), by Hadley Wickham and Garret Grolemund [@WickhamGrolemund2017].
+This book contains the **exercise solutions** for the book [*R for Data Science*](https://amzn.to/2aHLAQ1), by Hadley Wickham and Garret Grolemund [@WickhamGrolemund2017].
 
-*R for Data Science* itself is available online at [r4ds.had.co.nz](http://r4ds.had.co.nz/), and physical copy is published by O'Reilly Media and available from [amazon](http://amzn.to/2aHLAQ1).
+*R for Data Science* itself is available online at [r4ds.had.co.nz](https://r4ds.had.co.nz/), and physical copy is published by O'Reilly Media and available from [amazon](https://amzn.to/2aHLAQ1).
 
 ## Acknowledgments {-}
 
@@ -117,10 +117,10 @@ A special thanks to:
 -   [\@dongzhuoer](https://github.com/dongzhuoer) and [\@cfgauss](https://hypothes.is/users/cfgauss) for careful readings of the book and noticing numerous issues and proposing fixes.
 
 Thank you to all of those who contributed issues or pull-requests on
-[GitHub](https://github.com/jrnold/r4ds-exercise-solutions/graphs/contributors) 
+[GitHub](https://github.com/jrnold/r4ds-exercise-solutions/graphs/contributors)
 (in alphabetical order): `r github_contribs()`
 Thank you to all of you who contributed annotations on [hypothes.is](https://hypothes.is/search?q=url%3Ajrnold.github.io%2Fr4ds-exercise-solutions%2F*) (in alphabetical order): `r hypothesis_contribs()`.
 
 ## License {-}
 
-This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.
+This work is licensed under a <a rel="license" href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>.

intro.Rmd

@@ -15,7 +15,7 @@ The text for each exercise is followed by the solution.
 Like *R for Data Science*, packages used in each chapter are loaded in a code chunk at the start of the chapter in a section titled "Prerequisites".
 If exercises depend on code in a section of *R for Data Science* it is either provided before the exercises or within the exercise solution.
 
-If a package is used infrequently in solutions it may not be loaded, and functions using it will be called using the package name followed by two colons, as in `dplyr::mutate()` (see the *R for Data Science* [Introduction](http://r4ds.had.co.nz/introduction.html#running-r-code)).
+If a package is used infrequently in solutions it may not be loaded, and functions using it will be called using the package name followed by two colons, as in `dplyr::mutate()` (see the *R for Data Science* [Introduction](https://r4ds.had.co.nz/introduction.html#running-r-code)).
 The double colon may also be used to be explicit about the package from which a function comes.
 
 ## Prerequisites {-}
@@ -49,7 +49,7 @@ github_full_url <- stringr::str_c(SOURCE_URL, "tree", r_sha, sep = "/")
 ```
 
 HTML and PDF versions of this book are available at <`r PUB_URL`>.
-The book is powered by [bookdown](https://bookdown.org) which makes it easy to turn R markdown files into HTML, PDF, and EPUB.
+The book is powered by [bookdown](https://bookdown.org/home) which makes it easy to turn R markdown files into HTML, PDF, and EPUB.
 
 The source of this book is available on GitHub at <`r SOURCE_URL`>.
 This book was built from commit [`r r_sha_short`](`r github_full_url`).

iteration.Rmd

@@ -166,7 +166,7 @@ Combine your function writing and for loop skills:
 
 The answers to each part follow.
 
-1.  The lyrics for [Alice the Camel](http://www.kididdles.com/lyrics/a012.html) are:
+1.  The lyrics for [Alice the Camel](https://www.kididdles.com/lyrics/a012.html) are:
 
     > Alice the camel has five humps. \
     > Alice the camel has five humps. \
@@ -634,7 +634,7 @@ Write code that uses one of the map functions to:
     ```
 
 1.  To calculate the type of every column in `nycflights13::flights` apply
-    the function `typeof()`, discussed in the section on [Vector basics](http://r4ds.had.co.nz/vectors.html#vector-basics),
+    the function `typeof()`, discussed in the section on [Vector basics](https://r4ds.had.co.nz/vectors.html#vector-basics),
     and use `map_chr()`, since the results are character.
     ```{r}
     map_chr(nycflights13::flights, typeof)

model-basics.Rmd

@@ -148,7 +148,7 @@ best$par
 ```
 
 In practice, I suggest not using  `optim()` to fit this model, and instead using an existing implementation.
-The `rlm()` and `lqs()` functions in the [MASS](https://cran.r-project.org/package=MASS) fit robust and resistant linear models.
+The `rlm()` and `lqs()` functions in the [MASS](https://CRAN.R-project.org/package=MASS) fit robust and resistant linear models.
 
 </div>
 

model-building.Rmd

@@ -643,7 +643,7 @@ Write a small function to set the levels of the factor so that the week starts o
 
 <div class="answer">
 
-See the chapter [Factors](http://r4ds.had.co.nz/factors.html) for the function `fct_relevel()`.
+See the chapter [Factors](https://r4ds.had.co.nz/factors.html) for the function `fct_relevel()`.
 Use `fct_relevel()` to put all levels in-front of the first level ("Sunday").
 
 ```{r}