float random.uniform to 4 decimal places in python

I am having problem rounding floating value to a decimal number greater than 1.

def float_generator(size=6, chars = 6):
    return random.uniform(size,chars)

and i tried

target.write(str(float_generator(7,3)))

the above returns random float to 1 decimal num like 1.2222 , 1.333333 I want to generate 7 decimal and 3 points as illustrated in the 7,3

i tried rounding off below. It round up the points instead .

 target.write(str(format(float_generator(7,3),'.3f')))

Please how do i achieve 12345432.123 instead of 1.222343223 ? Any help would be appreciated.