Python - 指数中的位数

Question

是否可以设置用于打印浮点数指数的位数？我想把它设置为3.

目前,

f = 0.0000870927939438012
>>> "%.14e"%f
'8.70927939438012e-05'
>>> "%0.14e"%f
'8.709279e-005'

我想要打印的是: '8.70927939438012e-005'

Answer 1

没有办法控制它,最好的方法是为此编写一个函数

def eformat(f, prec, exp_digits):
    s = "%.*e"%(prec, f)
    mantissa, exp = s.split('e')
    # add 1 to digits as 1 is taken by sign +/-
    return "%se%+0*d"%(mantissa, exp_digits+1, int(exp))

print eformat(0.0000870927939438012, 14, 3)
print eformat(1.0000870927939438012e5, 14, 3)
print eformat(1.1e123, 4, 4)
print eformat(1.1e-123, 4, 4)

输出:

8.70927939438012e-005
1.00008709279394e+005
1.1000e+0123
1.1000e-0123

Answer 2

您可以使用np.format_float_scientific

from numpy import format_float_scientific

f = 0.0000870927939438012

format_float_scientific(f, exp_digits=3) # prints '8.70927939438012e-005'

format_float_scientific(f, exp_digits=5, precision=2) #prints '8.71e-00005'