"""
John Rachlin
DS 2000: Intro to Programming with Data


Date: Sun Sep 25 19:18:45 2022

File: reading_files.py
    
Description: 
    
    Three methods for reading comma-delimited file data into lists

Sample data:

Year,Cases (Millions)
2000,2.5
2001,3.7
2002,3.9
2003,2.8
2004,2.2
2005,1.9
    
    
"""


#%% READING FILE METHOD 1:
#   Read one line at a time using a WHILE loop


year = []
cases = []

with open("cases.csv", "r") as infile:
    
    header = infile.readline() # Skip the header if there is one
    line = infile.readline() 
    while line.strip() != '':  # There is more data!
        vals = line.split(",")
        year.append(int(vals[0]))
        cases.append(float(vals[1]))
        line = infile.readline()
        
print(year)
print(cases)


#%% READING FILE METHOD 2:
# Read all lines into a list of lines
# Use a loop to extract the data

year = []
cases = []

with open("cases.csv", "r") as infile:
   header = infile.readline()
   lines = infile.readlines()

index = 0
while index < len(lines):
    vals = lines[index].split(",")
    year.append(int(vals[0]))
    cases.append(float(vals[1]))
    index += 1
    
   
print(year)
print(cases)

#%% Plotting the data
plt.plot(year, cases, marker='o')