ex1_extract_data

# This is the homework 1， which requires us to extract all the numbers from a file and add them together.

# import and read text data
import re
hand = open('regex_sum_187445.txt')

# create a numlist, an empty set, to plug in all the numbers
numlist = []

# find out all the numbers and store them in 'extract'.
# () means extract all the elements inside the parentheses. [0-9]+ means one or more digits.
for line in hand:
    line = line.rstrip()
    extract = re.findall("([0-9]+)", line)
    
    # get rid of empty outcome.
    if len(extract) < 1 : continue

    # change the digits extracted to floating points.
    for i in range(len(extract)):
        num = float(extract[i])
        numlist.append(num)

print(sum(numlist))