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How to detect a floating point number using a regular expression
How do I write a Python regular expression that matches string representations of floating point numbers?
The expression should match any string that is accepted by the float constructor as in float('3.5'). Thus the expression should match '0.' and '.0' but not '.'
There is no need to match string representations of infinity and NaN.
834
[0-9]+|[0-9]+). This regular expression matches an optional sign, that is either followed by zero or more digits followed by a dot and one or more digits (a floating point number with optional integer part), or that is followed by one or more digits (an integer).
To extract a floating number from a string with Python, we call the re. findall method. import re d = re. findall("\d+\.
Introduction to the Python regex backreferences The backreferences allow you to reference capturing groups within a regular expression. In this syntax, N can be 1, 2, 3, etc. that represents the corresponding capturing group. Note that the \g<0> refer to the entire match, which has the same value as the match.
A repeat is an expression that is repeated an arbitrary number of times. An expression followed by '*' can be repeated any number of times, including zero. An expression followed by '+' can be repeated any number of times, but at least once.
r'[+-]?(\d+(\.\d*)?|\.\d+)([eE][+-]?\d+)?'
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