data sets :
https://www.ncei.noaa.gov/access/crn/qcdatasets.html
https://www.ncei.noaa.gov/pub/data/uscrn/products/monthly01/
weather data mining code
import java.io.IOException;
import java.util.Iterator;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.conf.Configuration;
public class MyMaxMin {
public static class MaxTemperatureMapper extends Mapper<LongWritable, Text, Text, Text>
{
public static final int MISSING=9999;
public void map(LongWritable arg0, Text Value, Context context) throws IOException, InterruptedException
{
String line = Value.toString();
if (!(line.length() == 0))
{
String date = line.substring(6, 14);
float temp_Min = Float.parseFloat(line.substring(39, 45).trim());
float temp_Max = Float.parseFloat(line.substring(47, 53).trim());
if (temp_Max > 35.0 && temp_Max!=MISSING)
{
context.write(new Text("Hot Day " + date),new Text(String.valueOf(temp_Max)));
}
if (temp_Min < 10 && temp_Max!=MISSING)
{
context.write(new Text("Cold Day " + date),new Text(String.valueOf(temp_Min)));
}
}
}
}
public static class MaxTemperatureReducer extends Reducer<Text, Text, Text, Text>
{
public void reduce(Text Key, Iterator<Text> Values, Context context)throws IOException, InterruptedException
{
String temperature = Values.next().toString();
context.write(Key, new Text(temperature));
}
}
public static void main(String[] args) throws Exception
{
Configuration conf = new Configuration();
Job job = new Job(conf, "weather example");
job.setJarByClass(MyMaxMin.class);
job.setMapOutputKeyClass(Text.class);
job.setMapOutputValueClass(Text.class);
job.setMapperClass(MaxTemperatureMapper.class);
job.setReducerClass(MaxTemperatureReducer.class);
job.setInputFormatClass(TextInputFormat.class);
job.setOutputFormatClass(TextOutputFormat.class);
Path OutputPath = new Path(args[1]);
FileInputFormat.addInputPath(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}