I like @ninjagecko's answer the most.

This would also work:

for Python 2.x

Use with AIisinstance(n, (int, long, float)) 

Python 3.x doesn't have long

Use with AIisinstance(n, (int, float))

there is also type complex for complex numbers

Maybe this can help you, is a separated function that if the given number is float return True or False

def is_float(number):
  if isinstance(number, float):
     return True
  else:
     return False

You can call it in your code like this, you pass the number in this case number_1 as a parameter:

if is_float(number_1):
  # do something

Python3 method to check for float:

def is_float(element: any) -> bool:
    #If you expect None to be passed:
    if element is None: 
        return False
    try:
        float(element)
        return True
    except ValueError:
        return False

Python2 version of the above: How do I parse a string to a float or int?

Always do unit testing. What is and is not a float may surprise you:

Command to parse                        Is it a float?  Comment
--------------------------------------  --------------- ------------
print(isfloat(""))                      False
print(isfloat("1234567"))               True 
print(isfloat("1_2_3.4"))               True        123.4, underscores ignored
print(isfloat("NaN"))                   True        nan is also float
print(isfloat("123.456"))               True
print(isfloat("123.E4"))                True
print(isfloat(".1"))                    True
print(isfloat("6.523537535629999e-07")) True
print(isfloat("6e777777"))              True        This is same as Inf
print(isfloat("-iNF"))                  True
print(isfloat("1.797693e+308"))         True
print(isfloat("infinity"))              True
print(isfloat("1,234"))                 False
print(isfloat("NULL"))                  False       case insensitive
print(isfloat("NaNananana BATMAN"))     False
print(isfloat(",1"))                    False           
print(isfloat("123.EE4"))               False           
print(isfloat("infinity and BEYOND"))   False
print(isfloat("12.34.56"))              False       Two dots not allowed.
print(isfloat("#56"))                   False
print(isfloat("56%"))                   False
print(isfloat("0E0"))                   True
print(isfloat("x86E0"))                 False
print(isfloat("86-5"))                  False
print(isfloat("True"))                  False       Boolean is not a float.   
print(isfloat(True))                    True        Boolean is a float
print(isfloat("+1e1^5"))                False
print(isfloat("+1e1"))                  True
print(isfloat("+1e1.3"))                False
print(isfloat("+1.3P1"))                False
print(isfloat("-+1"))                   False
print(isfloat("(1)"))                   False       brackets not interpreted

Sinking exceptions like this is bad, because killing canaries is bad because the float method can fail for reasons other than user input. Do not be using code like this on life critical software. Also python has been changing its contract on what unicode strings can be promoted to float so expect this behavior of this code to change on major version updates.