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/*
Yahoo Weather Forecast parser
http://developer.yahoo.com/weather/
This sketch demonstrate how to use the Linux command line tools
to parse a simple XML file on the Arduino Yún.
First thing download the XML file from the Yahoo Weather service
than use "grep" and "cut" to extract the data you want.
To find the location ID of your location, browse or search for your
city from the Weather home page. The location ID is in the URL for
the forecast page for that city.
created 21 Jun 2013
by Federico Vanzati
*/
#include <Bridge.h>
String locationID = "725003"; // Turin, Italy
// table with keywords to search in the XML file
// the third column is the tag to the field
String forecast[10][3] = {
"location", "2", "city",
"condition", "6", "temperature",
"condition", "2", "condition",
"astronomy", "2", "sunrise",
"astronomy", "4", "sunset",
"atmosphere", "2", "humidity",
"atmosphere", "6", "pressure",
"wind", "6", "wind speed",
"wind", "4", "wind direction",
"wind", "2", "chill temperature"
};
void setup() {
Bridge.begin();
Serial.begin(9600);
while(!Serial);
Serial.println("Weather Forecast for your location: \n");
}
void loop() {
for(int i=0; i<10; i++) {
// Compose the request
// curl is a program that connect to an URL an download the content
// is used to get the weather forecast from yahoo in XML format
String command = "curl -s "; // -s is the silent option
command += "http://weather.yahooapis.com/forecastrss"; // yahoo weather RSS service
command += "?w="; // query for the location
command += locationID;
//command += "\\&u=c"; // ask for celsius degrees
// add a new process
// grep is used to extract a single line of content containig a search keyword form the XML
command += " | "; // pipe a new process
command += "grep ";
command += forecast[i][0]; // word to search in the XML file
// add a new process
// cut is a program that split a text in different fields
// when encouter the passed character delimiter
command += " | "; // pipe a new process
command += "cut ";
command += "-d \\\" "; // -d parameter split the string every " char
command += "-f "; // -f parameter is to return the 6th splitted element
command += forecast[i][1]; // the field are already manually calculated and inserted in the forecast table
Serial.print(forecast[i][2]);
Serial.print("= ");
// run the command
Process wf;
wf.runShellCommand(command);
while(wf.available()>0)
{
Serial.print( (char)wf.read() );
}
}
//do nothing forevermore
while(1);
}
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