How can I print many significant figures in Python?

Question

For a scientific application I need to output very precise numbers, so I have to print 15 significant figures. There are already questions on this topic here, but they all c

Answer 1

To display N significant figures (not decimal places) you use the "g" format:

>>> x = 1.23
>>> print("%.2g" % x)
1.2
>>> x = 12.3
>>> print("%.2g" % x)
12

See format spec for details on precision:

The precision is a decimal number indicating how many digits should be displayed after the decimal point for a floating point value formatted with 'f' and 'F', or before and after the decimal point for a floating point value formatted with 'g' or 'G'. For non-number types the field indicates the maximum field size - in other words, how many characters will be used from the field content. The precision is not allowed for integer values.