{"id":422,"date":"2014-01-06T21:35:12","date_gmt":"2014-01-07T02:35:12","guid":{"rendered":"http:\/\/homepages.uc.edu\/~yaozo\/wordpress\/?p=422"},"modified":"2014-01-06T21:35:12","modified_gmt":"2014-01-07T02:35:12","slug":"how-to-create-an-attractive-choropleth-map-in-r","status":"publish","type":"post","link":"https:\/\/zhuoyao.net\/index.php\/2014\/01\/06\/how-to-create-an-attractive-choropleth-map-in-r\/","title":{"rendered":"How to create an attractive choropleth map in R?"},"content":{"rendered":"
\n\n\n\n
\n
\n
\n

I’ve been experimenting with choropleth mapping techniques in R, having reaped the benefits of ggplot2 for creating beautiful graphs within a powerful data analysis package.<\/p>\n

When it comes to mapping I’ve failed to produce results comparable to those I routinely get from QGIS. Using data of flow in Sheffield (fully replicable data and .qgs file\u00a0here<\/a>), QGIS easily produced the following:<\/p>\n

\"QGIS<\/p>\n

The best I could produce using R (using code described\u00a0here<\/a>) were these two maps, the first using GISTools, the second using ggplot2:<\/p>\n

\"GISTools\"ggplot2<\/p>\n

To me, the ggplot2 option seems far more attractive, if only I could solve the problem of the faulty lines (probably a problem with the fortify() command, or not reading in shapefiles using readOGR() describedhere<\/a>.)<\/p>\n

So the question is 2-fold: is the ggplot2 option the best choropleth mapping solution in R and, if so, how can I solve the problem of the faulty white lines?<\/p>\n

Replicable code to find out what I’ve done is\u00a0here<\/a>.<\/p>\n

Edit – Since made choropleth() output option more attractive:<\/strong><\/p>\n

\"New<\/p>\n

The ugliness of this option can be reduced by exporting at higher resolution and removing the legend (other R legends<\/a>\u00a0are available). Still not managed to change line thickness but it’s getting better! Red lines represent flows to zones which employ > 5000 people.<\/p>\n<\/div>\n

r<\/a>\u00a0thematic-map<\/a><\/div>\n\n\n\n\n
\n\n\n
<\/td>\n\n
<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n
\n
\n
\n
\n
active<\/a>oldest<\/a>votes<\/a><\/div>\n<\/div>\n<\/div>\n<\/div>\n

<\/a><\/p>\n

\n\n\n\n
\n\n
\n

There are some great resources on exactly this very interesting subject, including:<\/p>\n

From Revolutions:<\/p>\n

Choropleth Map R Challenge<\/a><\/p>\n

Choropleth Challenge Results<\/a><\/p>\n

From Stack Overflow.se:<\/p>\n

Developing Geographic Thematic Maps with R<\/a><\/p>\n

There are excellent examples of choropleth maps and their associated R code, including my favorite (i.e. attached map) using ggplot2. It should be relatively straight forward to insert your own data set into one of the script examples.<\/p>\n

R Code for this map available from\u00a0This is the Green Room<\/a><\/p>\n

\"\"<\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

I’ve been experimenting with choropleth mapping techniques in R, having reaped the benefits of ggplot2 for creating beautiful graphs within a powerful data analysis package.… <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-422","post","type-post","status-publish","format-standard","hentry","category-arcgis"],"_links":{"self":[{"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/posts\/422","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/comments?post=422"}],"version-history":[{"count":0,"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/posts\/422\/revisions"}],"wp:attachment":[{"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/media?parent=422"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/categories?post=422"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zhuoyao.net\/index.php\/wp-json\/wp\/v2\/tags?post=422"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}