I have a variable of int type.
I am running for loop on it and making a variable with adding some string info.
a = 5 // variable with integer value
list = '' // empty variable
for x in range(a):
list.append('MA[' + x + '] |')
Expected output:
MA[5] | MA[4] | MA[3] | MA[2] | MA[1] | MA[0]
As @Frank points out, list is a string which has no .append() method. You seriously should rename it to something more meaningful, but at the very least don't confuse the reader of your code (yourself included!) by naming a string list. Renaming it to string and using str() to cast x to a string:
string += 'MA[' + str(x) + '] |'
Or better, learn string formatting. In this case it would be:
string += 'MA[%d] | % x
You'll also need to change 5 t 6 if you want to iterate over the range 0-5 inclusive. And if you want to iterate in reverse, use range(a, -1, -1).
Here's a generator combined with join():
>>> ' | '.join('MA[%d]' % x for x in xrange(5, -1, -1))
'MA[5] | MA[4] | MA[3] | MA[2] | MA[1] | MA[0]'
Use string formatting. In Python 2.x:
list += ('MA[%s] |' % x)
The whole thing can more easily be written with a list comprehension and join:
my_list = ' | '.join('MA[%s]' % x for x in reversed(xrange(a)))
Also, don't call your variables list, that shadows the built-in function.
%d (is this the weFail question? :P)
%d and %s? Both give the same result here. Is %d faster?%d formats an integer, %s a string. Since x is an integer, best use %d.Here's a version with a generator expression:
>>> ' | '.join('MA[%s]' % x for x in range(5))
'MA[0] | MA[1] | MA[2] | MA[3] | MA[4]'
I also don't know why the other answers use .append. Strings don't have that method. Just because a variable is called list doesn't mean it is one.
Also note that your desired output is reversed. range(5) gives you [0,1,2,3,4] to iterate through. So your elements are created in the other order (from 0 up to 4) and do not include a 5..
list name.
'MA[{0}]'.format( x ) for x in range(5) instead of the % operator. % will go away in Python 3.To get what you want you need also to revert the list on which you iterate: very simple example:
a = 5
lst = ''
it_list = range(a+1)
it_list.reverse()
for x in it_list:
lst += 'MA[' + str(x) + '] |'
print lst[:-3]
Output:
MA[5] | MA[4] | MA[3] | MA[2] | MA[1] | MA[0]
Problems:
You are using a bad comment-string format - Python uses the pound char (#)
calling a variable 'list' is bad because it 'writes over' the list() constructor
worse, you are making "list" a string!
You are trying to use the list append() method - but because you have defined "list" as a string, and there is no string append() method, it fails
You are iterating backwards from the desired output (you are going '0 up to 4', not '5 down to 0')
You have an off-by-one error - Python does not include the last value in a range, so range(5) returns 0,1,2,3,4
Try:
def makeCallString(n, fmt="MA[{0}]", jn=" | "):
"Return string consisting of fmt[n] + jn + fmt[n-1] + jn + ... + fmt[0]"
return jn.join(fmt.format(a) for a in range(n, -1, -1))
Then
makeCallString(5)
returns
MA[5] | MA[4] | MA[3] | MA[2] | MA[1] | MA[0]
as a string.
AttributeError: 'str' object has no attribute 'append'. And apart from that,str.join- what you want can be written as' | '.join('MA[%d]' % i for i in ...).