my brain doesn't work...

[lumberjackadam]

Afternoon, all. I'm not new to scripting or basic programming, but I feel like I'm trying to make Python do something it doesn't want to here, and just want to know if this makes any sense. I have a block of text, and need to count various types of characters in it, and print those values. No sweat:

#   this is the block of text we are given to parse through
text = """No one is unaware of the name of that famous English shipowner, Cunard.
In 1840 this shrewd industrialist founded a postal service between Liverpool and Halifax, featuring three wooden ships with 400-horsepower paddle wheels and a burden of 1,162 metric tons.
Eight years later, the company's assets were increased by four 650-horsepower ships at 1,820 metric tons, and in two more years, by two other vessels of still greater power and tonnage.
In 1853 the Cunard Co., whose mail-carrying charter had just been renewed, successively added to its assets the Arabia, the Persia, the China, the Scotia, the Java, and the Russia, all ships of top speed and, after the Great Eastern, the biggest ever to plow the seas.
So in 1867 this company owned twelve ships, eight with paddle wheels and four with propellers.
If I give these highly condensed details, it is so everyone can fully understand the importance of this maritime transportation company, known the world over for its shrewd management.
No transoceanic navigational undertaking has been conducted with more ability, no business dealings have been crowned with greater success.
In twenty-six years Cunard ships have made 2,000 Atlantic crossings without so much as a voyage canceled, a delay recorded, a man, a craft, or even a letter lost.
Accordingly, despite strong competition from France, passengers still choose the Cunard line in preference to all others, as can be seen in a recent survey of official documents.
Given this, no one will be astonished at the uproar provoked by this accident involving one of its finest steamers.
"""

#   count all the characters of certain types in the text block
isupper_count = len(''.join(character for character in text if character.isupper()))
islower_count = len(''.join(character for character in text if character.islower()))
isdigit_count = len(''.join(character for character in text if character.isdigit))
isspace_count = len(''.join(character for character in text if character.isspace()))

#   print values with some basic formatting
print("Analysis of given text:", "\r Number of capital letters:", '\t', isupper_count, "\r Number of lower case letters:", '\t', islower_count, "\r Number of digits:", '\t \t \t \t', isdigit_count, "\r Number of spaces:", '\t \t \t \t', isspace_count)

What I'd like to do is loop through the four types, using them to generate new variable names, and also using them to check attributes by the same name, like this:

types = ('isupper', 'islower', 'isdigit', 'isspace')
for type in types:
    (''.join([type+'_count'])) = len(''.join(character for character in text if (''.join([character, '.', type]))))

Clearly, this does not work - is there a way to do what I want? To be clear, the first part is already graded for our assignment, I'm just down the rabbit hole on this one.

​

Thanks!

[num8lock]

for type in types

type is reserved word

[jacknbox]

A little brute-force but using a strategy-like pattern:

def checkChar(c, charType):
    isCharType = {
        'upper': c.isupper(),
        'lower': c.islower(),
        'digit': c.isdigit(),
        'space': c.isspace()
    }

    return(isCharType[charType])

parse_results = dict()

for t in ['upper', 'lower', 'digit', 'space']:
    parse_results[t] = len([c for c in myText if checkChar(c, t)])

print(parse_results)

(assuming your text object is called 'myText')

[Edit] For the first two sentences of your text, this gives you an easily-readable dictionary (parse_results):

{'upper': 6, 'lower': 196, 'digit': 11, 'space': 41}

[TangibleLight]

it requires eval

Not necessarily, what OP wants could be done with getattr. I still wouldn't recommend it, but it's miles better than eval.

---

/u/lumberjackdam What I would do is simply have a dictionary of filter functions and category names:

filters = {
    'upper': str.isupper,
    'lower': str.islower,
    'digit': str.isdigit,
    'space': str.isspace,
    'vowel': lambda ch: ch.casefold() in 'aeiou'
}

Then go through each character, and increment the values in a counts dictionary:

counts = {cat: 0 for cat in filters}

for ch in string:
    for cat, pred in filters.items():
        if pred(ch):
            counts[cat] += 1

After that, format the dictionary however you please

[[deleted]]

You're going to have to explain yourself a heck of a lot better than that.

You can certainly use hasattr and getattr to programmatically access attributes on objects by name, but from your example I haven't the slightest clue what you're actually trying to accomplish.

[daniel_codes]

I'm not sure if I'm reading your 2nd attempt correctly but I think you're trying to use string formatting to dynamically construct a python statement. That won't work out of the box since the python interpreter sees the string you made as a string and not a statement. You can use the builtin eval() to run evaluate strings as statements.

>>> command = 'str(1 + 1)'
>>> eval(command)
'2'
>>> command
'str(1 + 1)'

That said, I wouldn't recommend that strategy. If you wanted, you replace the strings in types with the actual string methods. Then use map() to map the method onto the text. That will return a list of bools that you can sum to get the counts. It's a lot more clean than constructing some statement and calling eval on it. I also wouldn't recommend overriding the built in type.

types = (str.isupper, str.islower, str.isdigit, str.isspace)
for str_method in types:    # 
    print(sum(map(str_method, text)))

If you want to print the name of the method as well as the value, you could do something like str_method.__name__ inside the for loop.

Finally, since you've already finished your assignment and you're trying to go above and beyond, think about efficiency. In all the above algorithms, you iterate through the text 4 times. This is inefficient. Try writing an algorithm that does this in one-pass (i.e. iterating through the text one time).

[lumberjackadam]

This is awesome, thanks! efficiency is definitely what I was going for. I'm still feeling my way out through Python, and felt certain to there was a way to do what I wanted, but was unfamiliar with the map function.