Concatenating objects of different types into a string (Python)

Question

I have been learning Python for two weeks now I created a function which displays your biographical data. I want to know how to put objects of different data types into one string

As you can see, the data includes strings, an int and a boolean. I want to be able to display them as a single string. So far my function only displays them individually like this: ('1000000', 'Bob', 17, False) I want to it display like this: '<1000000,Bob,17,False>'

def student_data(name, age, student_number, enrolled):
    age = int(age)
    true = "true"
    false = "false"
    # check to see if user is enrolled or not.
    if enrolled == true:        
        enrolled = True
    else:        
        enrolled = False
    data = (student_number, name, age, enrolled,) 
    return (data)

data = student_data("Jana", 17, "1001291657", "false")
print (data)

Please do not define 'true' and 'false' the way you have. VERY unpythonic. Just use the builtins True and False. Otherwise people will look at you funny... — dawg
– dawg, Commented Sep 14, 2014 at 22:18

dawg · Accepted Answer · 2014-09-15 21:21:04Z

The easy answer to the question 'Concatenating objects of different types into a string' is to use map:

>>> list_of_obj=['string', 1234, 123.4, {1:'one'}]
>>> map(str, list_of_obj)
['string', '1234', '123.4', "{1: 'one'}"]

Or a list comprehension:

>>> [str(e) for e in list_of_obj]
['string', '1234', '123.4', "{1: 'one'}"]

In each case, you are applying the built-in function str to each object in a list.

However, may I suggest writing a class to keep track of students:

class Student(object):
    def __init__(self, name, age, number, enrolled=True):
        self.name=name
        self.age=age
        self.number=number
        self.enrolled=enrolled

Then add a method to the class to format it the way you want:

    # Note indentation to be part of the class definition of Student...
    def __str__(self):
        seq=(self.name, self.age, self.number, self.enrolled)
        return '<{}>'.format(', '.join([str(e) for e in seq]))

Then create a student:

>>> student1=Student('Bob Jones', 23, 12345, True)

Then the format is as you define it to be:

>>> print student1   
<Bob Jone, 23, 12345, True>

As stated in the comments, I find it not so Pythonic to redefine true = "true" and false = "false" Just use True and False directly. The main reason, besides not confusing others (or yourself) is that you loose Python's sense of 'truthy' vs 'falsey':

>>> false = "false"
>>> bool(false)
True

Kasravnd · Accepted Answer · 2014-09-14 22:38:13Z

3

if you just want to show them ,simply use a function like this:

def student_data(name, age, student_number, enrolled):
 print "name:{0}, age:{1}, student_number:{2}, enrolled :{3}".fromat(name, age, student_number, enrolled)

and if you want to convert all of them to one string use this :

def student_data(name, age, student_number, enrolled):
   my_str=str(name)+','+str(age)+','+str(student_number)+','+str(enrolled)
   return my_str

as an alternative answer its better to pass your arguments in a list to function and use map and join built in functions for create a pythonic code for this aim :

my_list = [name, age, student_number, enrolled]
    def student_data(my_list):
     return ','.join(map(str,mylist))

edited Sep 14, 2014 at 22:38

answered Sep 14, 2014 at 22:16

Kasravnd

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2 Comments

Janarthanan Manoharan Over a year ago

Thanks for the feedback! The second method you showed was very easy to understand (Y)

Kasravnd Over a year ago

thanks ... there are many suggestion for a question like this as you see in answers but i answer base on your request ! so i will add another ways in edit to answer !

kecer · Accepted Answer · 2014-09-14 22:14:01Z

3

You can create a list of strings by converting your objects like this

[str(i) for i in data]

Then it's just a matter of joining the list together with join() method. Last lines of your code would look like this:

data = student_data("Jana", 17, "1001291657", "false")
string_data = ",".join([str(i) for i in data])
print("<{}>".format(string_data)) # adding brackets with format()

answered Sep 14, 2014 at 22:14

kecer

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