#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
ENGG1811 Lab

Data analysis on sea ice (Part 2)
"""

# %% Import packages
import numpy as np
import matplotlib.pyplot as plt 

# %% Preliminary processing 
# Load data and store it as a numpy array called data_sea_ice
data_sea_ice = np.loadtxt('sea_ice.txt')

# Extract information on year from data_sea_ice
years = data_sea_ice[:,0];   # first column
years = years.astype(int)    # change data type to int
data_sea_ice = np.delete(data_sea_ice,0,axis=1)   # remove the first column 

# Array on months 
months = np.linspace(0.5,12,24)

# The sea ice data began in year 1979 and lasted until 2013 (35 years)
# There are 24 half-monthly measurements per year

# years is the numpy array [1979, 1980, ..., 2013]
# months is the numpy array [0.5, 1, 1.5, ..., 12]
# data_sea_ice is a numpy array of shape (35,24) containing 
# sea ice extent 

# plot the data 
plt.figure(1)
plt.plot(months,np.transpose(data_sea_ice))
plt.xlabel("Months")
plt.xticks([2,4,6,8,10,12],["Feb","Apr","Jun","Aug","Oct","Dec"])
plt.ylabel("Sea ice extent")
plt.grid()
plt.show()

# %% ****************************
# Please insert your code below