Python Type Conversion

Question

Whats the best way to convert int's, long's, double's to strings and vice versa in python.

I am looping through a list and passing longs to a dict that should be turned into a unicode string.

I do

for n in l:  
    {'my_key':n[0],'my_other_key':n[1]}

Why are some of the most obvious things so complicated?

"passing longs to a dict that should be turned into a unicode string"? How is that "obvious"? What *are* you trying to accomplish? — S.Lott, Mar 03 '10 at 22:08
In JAVA, you can call the toString() method which you might think is obviously available in Python. And it does exist in Python via the str() method. Just not on the Object itself. — Dave, Mar 03 '10 at 22:44
"not on the Object itself". `str( anything )` works for every type there is -- by definition. For your own classes, `def __str__(self)` to tailor what is returned (it's like Java's `toString`) What actual problem are you having? Can you provide code and sample output? — S.Lott, Mar 04 '10 at 01:39

score 37 · Answer 1 · answered Mar 03 '10 at 22:02

37

To convert from a numeric type to a string:

str(100)

To convert from a string to an int:

int("100")

To convert from a string to a float:

float("100")

answered Mar 03 '10 at 22:02

Mark Byers

Thanks, I found it in the docs. But I appreciate your answer very much. – Dave Mar 03 '10 at 22:39
This is a much better answer. I don't know why it's not the accepted answer. – Scott Tesler Nov 15 '13 at 16:06
@ScottDavidTesler I think I am the only that repeatedly said that lines in SO ;) – swdev Apr 10 '14 at 16:42

score 2 · Accepted Answer · answered Mar 03 '10 at 22:09

2

You could do it like this in Python 2.x:

>>> l = ((1,2),(3,4))
>>> dict(map(lambda n: (n[0], unicode(n[1])), l))
{1: u'2', 3: u'4'}

or in Python 3.x:

>>> l = ((1,2),(3,4))
>>> {n[0] : str(n[1]) for n in l}
{1: '2', 3: '4'}

Note that strings in Python 3 are the same as unicode strings in Python 2.

answered Mar 03 '10 at 22:09

AndiDog

The way the OP uses n[0] doesn't look like it's a key – John La Rooy Mar 03 '10 at 22:28
This cide, while a working one, is also very hard to read. Code is read more than it is written, and that's why you should use code from Mark Byers answer. – Błażej Michalik Jun 08 '15 at 21:23

John La Rooy · Answer 3 · 2010-03-03T22:38:25.057

0

You can do it this way

for n in l:
    {'my_key':unicode(n[0]),'my_other_key':unicode(n[1])}

Perhaps this is clearer if there are only 2 or 3 keys/values

for my_value, my_other_value in l:
    {'my_key':unicode(my_value),'my_other_key':unicode(my_other_value)}

I think this would be better if there are more than 3 keys/values

for n in l:
    dict(zip(('my_key','myother_key'),map(unicode,n)))

edited Mar 03 '10 at 22:38

answered Mar 03 '10 at 22:33

John La Rooy

3 Answers3