Python Lambda, Filtering Out Non Alpha Characters

i'm trying to keep only the letters in a string. i am trying to do something like this: s = '1208uds9f8sdf978qh39h9i#H(&#*H(&H97dgh' s_ = lambda: letter if letter.isalpha()

Solution 1:

Alternately:

s_ = filter(lambda c: c.isalpha(), s)

Solution 2:

how about

re.sub('[^a-zA-Z]','', s)

or

"".join([x for x in s if x.isalpha()])

Solution 3:

One handy way to manipulate strings is using a generator function and the join method:

result = "".join( letter for letter in s if letter.isalpha() )

Solution 4:

You don't need a lambda function:

result = ''.join(c for c in input_str if c.isalpha())

If you really want to use a lambda function you could write it as follows:

result = ''.join(filter(lambda c:str.isalpha(c), input_str))

But this can also be simplified to:

result=''.join(filter(str.isalpha, input_str))

Solution 5:

You probably want a list comprehension here:

s_ = [letter for letter in s if letter.isalpha()]

However, this will give you a list of strings (each one character long). To convert this into a single string, you can use join:

s2 = ''.join(s_)

If you want, you can combine the two into a single statement:

s_ = ''.join(letter for letter in s if letter.isalpha())

If you particularly want or need to use a lambda function, you can use filter instead of the generator:

my_func = lambda letter: letter.isalpha()
s_ = ''.join(filter(my_func, s))