How do I limit the number of digits in a list?

This is a small piece of code that I am writing for an chemistry ab initio program. I am having issues making the C1pos list a number with exactly 6 digits after the decimal place. I have tried several methods such as the decimal function, but so far I am having no luck.

Position is a definition that will take a matrix (1,1,1)+(1,1,1) and give you (2,2,2) numpy is not installed on my server.

class Position:

    def __init__(self, data):
        self.data = data

    def __repr开发者_开发百科__(self):
        return repr(self.data)  

    def __add__(self, other):

        data = [] #start with an empty list

        for j in range(len(self.data)):

            data.append(self.data[j] + other.data[j])

        return Position(data) 


deltaa=2.000001
#Set number of steps +1
numx=2
numy=1
numz=1
Carbon=[1.070000,0.000000,0.000000]
startpos=[1.000000,1.000000,1.000000]
l=[]
top=os.getcwd()
lgeom=[]
for i in range(numx):
    for j in range(numy):
        for h in range(numz):
            l=i, j, h
            shift=list(l)
            shiftdist=[ k*deltaa for k in shift] 
            C1pos=Position(Carbon)+Position(shiftdist)+Position(startpos)
            ltempl[10]=' C1,'+str(C1pos).strip('[]').replace(' ','') 

Any suggestions?

EG: The output needs to be C1,2.123456,3.123456,4.123456 The number will never surpass 10.

','.join("%.6f" % f for f in C1pos)

Example

C1pos = [2.123, 300.123456, 4.123456789]
print ','.join("%.6f" % f for f in C1pos)

Output

2.123000,300.123456,4.123457

you can use the decimal class to round all your numbers to 6 decimal places.

from decimal import Decimal, ROUND_UP

Decimal(n).quantize(Decimal('.000001'), rounding=ROUND_UP)

or if you are doing this operation on a string (as i suspect from your code):

print ('C1,' + ','.join(["%.6f" %x for x in C1pos]))