String formatting for hex colors in Python

Question

I modified a function from PHP to return a color gradient (http://www.herethere.net/~samson/php/color_gradient/color_gradient_generator.php.txt). I am having issues when returning color hex codes ending in 0s. This is the function:

def _get_color(current_step=0, start='000000', end='ffffff', max_steps=16):
    '''
        Returns the color code for current_step between start and end
    '''
    start = '{0:#x}'.format(int(start, 16))
    end = '{0:#x}'.format(int(end, 16))

    if int(max_steps) > 0 & int(max_steps) < 256:
        max_steps = max_steps
    else:
       max_steps = 16

    r0 = (int(start, 16) & 0xff0000) >> 16
    g0 = (int(start, 16) & 0x00ff00) >> 8
    b0 = (int(start, 16) & 0x0000ff) >> 0

    r1 = (int(end, 16) & 0xff0000) >> 16
    g1 = (int(end, 16) & 0x00ff00) >> 8
    b1 = (int(end, 16) & 0x0000ff) >> 0

    if r0 < r1:
        r = int(((r1-r0)*(float(current_step)/float(max_steps)))+r0)
    else:
        r = int(((r0-r1)*(1-(float(current_step)/float(max_steps))))+r1)

    if g0 < g1:
        g = int(((g1-g0)*(float(current_step)/float(max_steps)))+g0)
    else:
        g = int(((g0-g1)*(1-(float(current_step)/float(max_steps))))+g1)

    if b0 < b1:
        b = int(((b1-b0)*(float(current_step)/float(max_steps)))+b0)
    else:
        b = int(((b0-b1)*(1-(float(current_step)/float(max_steps))))+b1)

    return '{0:#x}'.format(((((r << 8) | g) << 8) | b))

When I run a loop staring at #000000 which is black, I only return 0. The second code, f0f0f, is also missing a 0.

for i in range(0, 16):
    print _get_color(current_step=i, start='000000', end='ffffff', max_steps=16)

0
f0f0f
1f1f1f
2f2f2f
3f3f3f
4f4f4f
5f5f5f
6f6f6f
7f7f7f
8f8f8f
9f9f9f
afafaf
bfbfbf
cfcfcf
dfdfdf
efefef

Notice the first two hex codes. Any thoughts on how to format the return value properly to return 000000?

Answer 1

>>> print '{0:06x}'.format(123)
00007b