davidcoallier

davidcoallier

Mapping the Streets of Ireland With R and ggplot2

Earlier today an interesting article about plotting the streets of france appeared in my feed. What Simon does in his blog post is essentially read OSM street-lines-data for France and displays it in what I find to be a rather traditional and elegant way.

The first thing I immediately though of was: "I'd love to see this for Ireland". As an OSX user, it took a few tricks to get the article replicated for Ireland therefore I've decided to share my notes.

Should you wish to replicate this for your country, here are some notes I've taken.

Get The Data

davidcoallier

Load Data With Hmisc

Often times when working with data in R, you find yourself needing to summarise a data.frame by a column, a SELECT SUM(..) or SELECT COUNT(..) in MySQL if you will.

For instance, you may have a lot of page-visits to analyse and you aren't quite certain how to summarise some of that data using R.

Let's consider the following (trivial) dataset:

davidcoallier

require(RColorBrewer)
require(ggplot2)
require(scales)

# Thanks to drew conway for this handy function.
get.stack<-function(tok) {
    # Must check for XML install, thanks onertipaday!
    if (!require(XML)) install.packages('XML')
    library(XML)
    # Enter a SO tag as character string, and number of tags are returned

davidcoallier

Year    Divided	Unified D	Unified R
1938	10	21	15
1940	15	19	12
1942	9	17	20
1944	10	18	18
1946	8	17	21
1948	15	18	13
1950	15	15	16
1952	8	14	24
1954	16	16	14

davidcoallier

function [maxtab, mintab]=peakdet(v, delta, x)
%PEAKDET Detect peaks in a vector
%        [MAXTAB, MINTAB] = PEAKDET(V, DELTA) finds the local
%        maxima and minima ("peaks") in the vector V.
%        MAXTAB and MINTAB consists of two columns. Column 1
%        contains indices in V, and column 2 the found values.
%      
%        With [MAXTAB, MINTAB] = PEAKDET(V, DELTA, X) the indices
%        in MAXTAB and MINTAB are replaced with the corresponding
%        X-values.

davidcoallier

> x <- c(1,3,6,9,12)
> y <- c(1.5,2,7,8,15)
> plot(x,y)

 *** caught segfault ***
address 0x0, cause 'memory not mapped'

davidcoallier

$ ./sapi/cli/php -r 'print_r([1, 2, 3]);'
Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)

davidcoallier

#!/usr/bin/perl

##############
# udp flood.
##############

use Socket;
use strict;

my $argc = @ARGV + 1;

davidcoallier

-- 
-- Is there a better way to celebrate ones birthday than
-- generating an Ascii cake and some text-output wishin
-- happy birthday to the person I consider one of the most
-- important person in the history of automated computation.
-- 
-- Note:
-- Compile with gcc after having installed GNAT (If on OSX)
-- $> gcc -c happybirthdayadatask.adb
-- $> gnatbl -o happybirthday happybirthdayadatask.ali