How i print each second element in a list full of lines? Python

Question

I have a list of numbers like this(saved in .txt file):

list_of_numbers = [
   ('5', 2.5, 5200),
   ('6', 3.2, 5236),
   ('8', 5.4, 5287),
   ('6', 8.7, 2563)
]

And i imported this list (list is .txt file) like this:

list_of_numbers = open("list_of_numbers.txt").read().strip().split()

but now i want that python print me each second element in each line.. I tried this:

p = x[1] for x in list_of_numbers
print(p)

but it's not correct.. And i want that python printed me like this:

p = 2.5, 3.2, 5.4

Please help me..

Answer 1

You missed the brackets. Try this:

p = [x[1] for x in list_of_numbers]

To print the values, you could use

print(', '.join([str(x) for x in p]))

You also need to change the way you load the data from the file

Full Code:

def parse(raw):
    data = []
    for line in raw.split("\n"):
        line = line.strip()
        # --> "('5', 2.5, 5200)"
        if line.startswith("(") and line.endswith(")"):
            d = line[line.index("(")+1 : line.index(")", -1)]
            # --> "'5', 2.5, 5200"
            d = d.split(",")
            data.append([])
            for i in d:
                i = i.strip()
                try:
                    i = float(i)
                except:
                    pass
                data[-1].append(i)
    return data


raw = open("list_of_numbers.txt").read()

list_of_numbers = parse(raw)

p = [x[1] for x in list_of_numbers]
# --> [2.5, 3.2, 5.4, 8.7]
print(', '.join([str(x) for x in p]))
# ---> 2.5, 3.2, 5.4, 8.7

I suggest using pickle. Storing and loading your data is easy as:

import pickle
data = ...
# store
file = open('data.txt', 'w')
pickle.dump(data, file)
file.close()
# load
file = open('data.txt', 'r')
data = pickle.load(file)
file.close()