Python - making a function that would add "-" between letters

Question

I'm trying to make a function, f(x), that would add a "-" between each letter:

For example:

f("James")

should output as:

J-a-m-e-s-

I would love it if you could use simple python functions as I am new to programming. Thanks in advance. Also, please use the "for" function because it is what I'm trying to learn.

Edit:

yes, I do want the "-" after the "s".

@TigerhawkT3 posted it as a comment because i don't know what exactly that op wants. — Avinash Raj, Apr 01 '15 at 03:28
James @spam answer is best (in my view) even if you want suffix `-` after `s` then add it explicitly as commented their — Grijesh Chauhan, Apr 01 '15 at 03:35

score 8 · Answer 1 · edited May 23 '17 at 11:43

8

Can I try like this:

>>> def f(n):
...     return '-'.join(n)
...
>>> f('james')
'j-a-m-e-s'
>>>

Not really sure if you require the last 'hyphen'.

Edit:

Even if you want suffixed '-', then can do like

def f(n):
   return '-'.join(n) + '-'

As being learner, it is important to understand for your that "better to concat more than two strings in python" would be using str.join(iterable), whereas + operator is fine to append one string with another.

Please read following posts to explore further:

edited May 23 '17 at 11:43

Community

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answered Apr 01 '15 at 03:20

James Sapam

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I like your post as first post and added few more details as I notice OP is new, please check updated answer, if don't like then edit/revert. good luck. – Grijesh Chauhan Apr 01 '15 at 03:53
As of Python 2.6 (I think) it is actually faster to use ```+=``` then to use ```str.join()```. Sorry I forget the source, but feel free to ```timeit``` yourself. – pzp Apr 01 '15 at 04:02
@pzp1997 yes to add two strings `+=` would be better than `str.join` : check here: http://stackoverflow.com/questions/12169839/which-is-better-to-concat-a-string-in-python – Grijesh Chauhan Apr 01 '15 at 04:04
That was actually the source that I was referring to. And according to that ```+=``` is faster than ```str.join()``` in EVERY case. Even when concatenating 100,000 one hundred character strings += is faster (and I doubt anyone would ever reasonably need to do something that extreme). Part of the reason might be because it takes more time to resolve ```str.join()``` than ```+=```, which is an operator. – pzp Apr 01 '15 at 04:13
Then Pep8 needs to be updated: `Code should be written in a way that does not disadvantage other implementations of Python [snip]. For example, do not rely on CPython's efficient implementation of in-place string concatenation for statements in the form a += b or a = a + b. [snip] In performance sensitive parts of the library, the ''.join() form should be used instead.` – AChampion Apr 01 '15 at 04:40

Avinash Raj · Accepted Answer · 2015-04-01T04:45:39.890

5

Also, please use the "for" function because it is what I'm trying to learn

>>> def f(s):
        m = s[0]
        for i in s[1:]:
             m += '-' + i
        return m

>>> f("James")
'J-a-m-e-s'

m = s[0] character at the index 0 is assigned to the variable m
for i in s[1:]: iterate from the second character and
m += '-' + i append - + char to the variable m
Finally return the value of variable m

If you want - at the last then you could do like this.

>>> def f(s):
        m = ""
        for i in s:
            m +=  i + '-'
        return m

>>> f("James")
'J-a-m-e-s-'

edited Apr 01 '15 at 04:45

answered Apr 01 '15 at 03:24

Avinash Raj

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"Because it is what **I'm trying to learn**," --- if someone trying to learn then posting an unexplained code is not that much helpful. You should tell why your code is not bad in Python -- (don't suggest C kindof code in Python) – Grijesh Chauhan Apr 01 '15 at 03:37
Avinash every code in computer runs in 0s and 1s form, how much internal you would like to tech him? I was just telling some obvious explanation this question and python. check @sapam's answer. – Grijesh Chauhan Apr 01 '15 at 03:58
anyways, your answer is good because OP specially request for "for" loop code. – Grijesh Chauhan Apr 01 '15 at 04:05
unnecessary to pop off the first list item because the OP wants a final -, so `for i in s: m += i + '-'` would achieve this. Though I'm not a great fan of string concatenation, strings are immutable so this can be expensive. – AChampion Apr 01 '15 at 04:35

score 2 · Answer 3 · answered Apr 01 '15 at 03:20

2

text_list = [c+"-" for c in text]
text_strung = "".join(text_list)

answered Apr 01 '15 at 03:20

Alexander R.

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AChampion · Answer 4 · 2015-04-01T04:32:34.923

1

Given you asked for a solution that uses for and a final -, simply iterate over the message and add the character and '-' to an intermediate list, then join it up. This avoids the use of string concatenations:

>>> def f(message)
        l = []
        for c in message:
            l.append(c)
            l.append('-')
        return "".join(l)
>>> print(f('James'))
J-a-m-e-s-

edited Apr 01 '15 at 04:32

answered Apr 01 '15 at 03:23

AChampion

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score 1 · Answer 5 · answered Apr 01 '15 at 04:24

1

As a function, takes a string as input.

def dashify(input):
    output = ""
    for ch in input:
        output = output + ch + "-"
    return output

answered Apr 01 '15 at 04:24

MadMan2064

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score 0 · Answer 6 · edited May 23 '17 at 12:22

I'm sorry, but I just have to take Alexander Ravikovich's answer a step further:

f = lambda text: "".join([c+"-" for c in text])

print(f('James'))  # J-a-m-e-s-

It is never too early to learn about list comprehension.

"".join(a_list) is self-explanatory: glueing elements of a list together with a string (empty string in this example).

lambda... well that's just a way to define a function in a line. Think

square = lambda x: x**2
square(2)  # returns 4
square(3)  # returns 9

Python is fun, it's not {enter-a-boring-programming-language-here}.

Python - making a function that would add "-" between letters

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