fix link redirects

README.Rmd

@@ -24,7 +24,7 @@ knitr::opts_chunk$set(
 */dʒiː.dʒɪˈrɑːf/*  (or g-giraffe)
 
 ## A grammar of graphics for relational data
-ggraph is an extension of [`ggplot2`](http://ggplot2.tidyverse.org) aimed at
+ggraph is an extension of [`ggplot2`](https://ggplot2.tidyverse.org) aimed at
 supporting relational data structures such as networks, graphs, and trees. 
 While it builds upon the foundation of `ggplot2` and its API it comes with its
 own self-contained set of geoms, facets, etc., as well as adding the concept of 
@@ -50,18 +50,18 @@ ggraph(graph, layout = 'kk') +
 ### The core concepts
 `ggraph` builds upon three core concepts that are quite easy to understand:
 
-1. [**The Layout**](http://www.data-imaginist.com/2017/ggraph-introduction-layouts/) 
+1. [**The Layout**](https://www.data-imaginist.com/2017/ggraph-introduction-layouts/) 
 defines how nodes are placed on the plot, that is, it is a 
 conversion of the relational structure into an x and y value for each node in 
 the graph. `ggraph` has access to all layout functions available in `igraph` and
 furthermore provides a large selection of its own, such as hive plots, treemaps,
 and circle packing.
-2. [**The Nodes**](http://www.data-imaginist.com/2017/ggraph-introduction-nodes/) 
+2. [**The Nodes**](https://www.data-imaginist.com/2017/ggraph-introduction-nodes/) 
 are the connected entities in the relational structure. These 
 can be plotted using the `geom_node_*()` family of geoms. Some node geoms make
 more sense for certain layouts, e.g. `geom_node_tile()` for treemaps and icicle
 plots, while others are more general purpose, e.g. `geom_node_point()`.
-3. [**The Edges**](http://www.data-imaginist.com/2017/ggraph-introduction-edges/) 
+3. [**The Edges**](https://www.data-imaginist.com/2017/ggraph-introduction-edges/) 
 are the connections between the entities in the relational 
 structure. These can be visualized using the `geom_edge_*()` family of geoms 
 that contain a lot of different edge types for different scenarios. Sometimes

README.md

@@ -17,7 +17,7 @@ coverage](https://codecov.io/gh/thomasp85/ggraph/branch/master/graph/badge.svg)]
 
 ## A grammar of graphics for relational data
 
-ggraph is an extension of [`ggplot2`](http://ggplot2.tidyverse.org)
+ggraph is an extension of [`ggplot2`](https://ggplot2.tidyverse.org)
 aimed at supporting relational data structures such as networks, graphs,
 and trees. While it builds upon the foundation of `ggplot2` and its API
 it comes with its own self-contained set of geoms, facets, etc., as well
@@ -55,21 +55,21 @@ ggraph(graph, layout = 'kk') +
 understand:
 
 1.  [**The
-    Layout**](http://www.data-imaginist.com/2017/ggraph-introduction-layouts/)
+    Layout**](https://www.data-imaginist.com/2017/ggraph-introduction-layouts/)
     defines how nodes are placed on the plot, that is, it is a
     conversion of the relational structure into an x and y value for
     each node in the graph. `ggraph` has access to all layout functions
     available in `igraph` and furthermore provides a large selection of
     its own, such as hive plots, treemaps, and circle packing.
 2.  [**The
-    Nodes**](http://www.data-imaginist.com/2017/ggraph-introduction-nodes/)
+    Nodes**](https://www.data-imaginist.com/2017/ggraph-introduction-nodes/)
     are the connected entities in the relational structure. These can be
     plotted using the `geom_node_*()` family of geoms. Some node geoms
     make more sense for certain layouts, e.g. `geom_node_tile()` for
     treemaps and icicle plots, while others are more general purpose,
     e.g. `geom_node_point()`.
 3.  [**The
-    Edges**](http://www.data-imaginist.com/2017/ggraph-introduction-edges/)
+    Edges**](https://www.data-imaginist.com/2017/ggraph-introduction-edges/)
     are the connections between the entities in the relational
     structure. These can be visualized using the `geom_edge_*()` family
     of geoms that contain a lot of different edge types for different