Output formatting error for positive numbers in scientific notation with long mantissas and negative exponents

[LiemuR]

Describe the bug
When outputting positive numbers in scientific notation with a long mantissa and negative exponent, the leading digit of the number is incorrectly replaced with a minus sign.
For example:​​
The positive number 1.11111111e-5 is incorrectly formatted as -.111e-05. This can be misleading because while the latter is a valid float representation in Python, it represents a completely different (and negative) value.

To Reproduce

from bayes_opt import BayesianOptimization

optimizer = BayesianOptimization(f=lambda x: x, pbounds={"x": (-1, 1)})
optimizer.probe({"x": 1.11111111e-5})
optimizer.maximize(init_points=0, n_iter=0)

Expected behavior
The leading digit of the number should not be replaced with a minus sign.

Screenshots
Result of running code snippet:

Environment

• OS: Windows
• python Version 3.13.3
• numpy Version 2.2.6
• scipy Version 1.15.2
• bayesian-optimization Version 3.1.0

[t-muser]

Ugh the formatting really keeps on haunting us. Thanks for reporting @LiemuR! :) @adrianmolzon would you maybe have time to look at this?

[adrianmolzon]

Ooph yeah I can take a look, that's a silly bug. Thanks for reporting!

[adrianmolzon]

#590

[t-muser]

should be fixed! :)