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Converting list of strings to int

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#1

Screen Link:
https://app.dataquest.io/c/62/m/351/cleaning-and-preparing-data-in-python/8/parsing-numbers-from-complex-strings-part-two

My Code: 

test_data = ["1912", "1929", "1913-1923",
             "(1951)", "1994", "1934",
             "c. 1915", "1995", "c. 1912",
             "(1988)", "2002", "1957-1959",
             "c. 1955.", "c. 1970's", 
             "C. 1990-1999"]

bad_chars = ["(",")","c","C",".","s","'", " "]

def strip_characters(string):
    for char in bad_chars:
        string = string.replace(char,"")
    return string

stripped_test_data = ['1912', '1929', '1913-1923',
                      '1951', '1994', '1934',
                      '1915', '1995', '1912',
                      '1988', '2002', '1957-1959',
                      '1955', '1970', '1990-1999']

def process_date(string):
    if "-" in string:
        dates = string.split("-")
        for year in dates:
            year = int(year)
        
        #dates = [int(year) for year in dates]

        update = round(sum(dates)/2)
    else:
        update = int(string)
    return update

processed_test_data = []
for date in stripped_test_data:
    update = process_date(date)
    processed_test_data.append(update)
    
for row in moma:
    date = row[6]
    date = strip_characters(date)
    date = process_date(date)
    row[6] = date

What I expected to happen:
I expected the

        for year in dates:
            year = int(year)

portion of my code to work as how the commented out line below it does:

dates = [int(year) for year in dates]

What actually happened:
To my understanding, it seems that the for loop is not converting all elements to int.

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-1-17c6921909ff> in <module>
     88 processed_test_data = []
     89 for date in stripped_test_data:
---> 90     update = process_date(date)
     91     processed_test_data.append(update)
     92 

<ipython-input-1-17c6921909ff> in process_date(string)
     81         #dates = [int(year) for year in dates]
     82 
---> 83         update = round(sum(dates)/2)
     84     else:
     85         update = int(string)

TypeError: unsupported operand type(s) for +: 'int' and 'str'
#2

I ran your code and it didn’t throw any errors. Are you sure you shared all the code?

I recommend refreshing the page and running the code again.

#3

I have updated my post to reflect the version that throws me the error. I had it commented out before so it would stand out, sorry!

#4

Yes, that’s what’s happening.

The year in the above loop gets updated but the list item is separate from that variable year, to put it simply.

You can -

  • Use list comprehensions (like you did), or
  • Create a new list and append the modified values to that new list, or
  • Iterate over the indices using either range() or enumerate() and then update the values using something like dates[idx]
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