Convert scientific notation to decimals

I’m pretty sure you can do this with:

float("8.99284722486562e-02")
# and now with 'rounding'
"{:.8f}".format(float("8.99284722486562e-02"))

The scientific notation can be converted to a floating point number with float.

   In [1]:  float("8.99284722486562e-02")
Out [1]:   0.0899284722486562

The float can be rounded with format and then float can be used on the string to return the final rounded float.

   In [2]:  float("{:.8f}".format(float("8.99284722486562e-02")))
Out [2]:   0.08992847

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2022 edit for No Sound’s comment:

I learned this solution from here (archived)

The following solutions work for larger numbers.

Solution 1)

import numpy as np

print(np.format_float_positional(1.32456e-12, trim='-'))
print(np.format_float_positional(1.32456e-24, trim='-'))
print(np.format_float_positional(1.32456e12, trim='-'))
print(np.format_float_positional(1.32456e24, trim='-'))

# Output: 0.00000000000132456
#         0.00000000000000000000000132456
#         1324560000000
#         1324560000000000000000000

Solution 2)

same as above accept this time using a lambda function

import numpy as np

pretty_print = lambda x: np.format_float_positional(x, trim="-")

print(pretty_print(1.32456e-12))
print(pretty_print(1.32456e-24))
print(pretty_print(1.32456e12))
print(pretty_print(1.32456e24))

# Output: 0.00000000000132456
#         0.00000000000000000000000132456
#         1324560000000
#         1324560000000000000000000

As you may know floating point numbers have precision problems. For example, evaluate:

>>> (0.1 + 0.1 + 0.1) == 0.3
False

Instead you may want to use the Decimal class. At the python interpreter:

>>> import decimal
>>> tmp = decimal.Decimal('8.99284722486562e-02')
Decimal('0.0899284722486562')
>>> decimal.getcontext().prec = 7
>>> decimal.getcontext().create_decimal(tmp)
Decimal('0.08992847')