Step 1: Sample Weather Dataset 
Year, Temperature 
2018,30 
2018,32 
2018,29 
2019,35 
2019,33 
2019,31 
2020,36 
2020,38 
2020,37 
Mapper Code (mapper.py) 
import sys 
for line in sys.stdin: 
line = line. Strip() 
if line.startswith("Year"): 
continue 
year, temp = line.Split(",") 
print(f"{year}\t{temp}") 
Reducer Code (reducer.py) 
import sys 
current_year = None 
max_temp = -999 
for line in sys.stdin: 
line = line.strip() 
year, temp = line.split("\t") 
temp = int(temp) 
if current_year == year: 
max_temp = max(max_temp, temp) 
else: 
if current_year: 
print(f"{current_year}\t{max_temp}") 
current_year = year 
max_temp = temp 
if current_year == year: 
print(f"{current_year}\t{max_temp}") 
Google Colab Implementation Code 
# Upload dataset 
from google.colab import files 
uploaded = files.upload() 
# Install Hadoop 
!apt-get install openjdk-8-jdk-headless -qq > /dev/null 
!wget -q https://downloads.apache.org/hadoop/common/hadoop-3.3.6/hadoop
3.3.6.tar.gz 
!tar xf hadoop-3.3.6.tar.gz 
# Create Mapper File 
%%writefile mapper.py 
import sys 
for line in sys.stdin: 
line=line.strip() 
if line.startswith("Year"): 
continue 
year,temp=line.split(",") 
print(f"{year}\t{temp}") 
# Create Reducer File 
%%writefile reducer.py 
import sys 
current_year=None 
max_temp=-999 
for line in sys.stdin: 
    line=line.strip() 
    year,temp=line.split("\t") 
    temp=int(temp) 
 
    if current_year==year: 
        max_temp=max(max_temp,temp) 
    else: 
        if current_year: 
            print(f"{current_year}\t{max_temp}") 
        current_year=year 
        max_temp=temp 
 
if current_year==year: 
    print(f"{current_year}\t{max_temp}") 
# Run MapReduce 
!cat weather.csv | python mapper.py | sort | python reducer.py