Celsius to Fahrenheit Conversions (#2188)

* added conversions between celsius and fahrenheit

* Renamed celsius_to_fahrenheit.py

* Fixed spelling issues

* modified file to fit the 88-character limit

* added changes to pass the travis-ci test

* further changed the files to pass the travis-ci test

* further changed the files to pass the travis-ci test

* Shortened conversions/fahrenheit_to_celsius.py

Co-authored-by: Christian Clauss <cclauss@me.com>

* Type hints added to conversions/fahrenheit_to_celsius.py

Co-authored-by: Christian Clauss <cclauss@me.com>

* changed the code to let the caller do the printing

* addressed the changes made on github

* Added Kelvin conversions and put temperature functions in a single file

* Removed whitespace from a blank line

* Update temperature_conversions.py

Co-authored-by: Christian Clauss <cclauss@me.com>

conversions/temperature_conversions.py

@@ -0,0 +1,88 @@
+""" Convert between different units of temperature """
+
+
+def celsius_to_fahrenheit(celsius: float) -> float:
+    """
+    Convert a given value from Celsius to Fahrenheit and round it to 2 decimal places.
+
+    >>> celsius_to_fahrenheit(-40.0)
+    -40.0
+    >>> celsius_to_fahrenheit(-20.0)
+    -4.0
+    >>> celsius_to_fahrenheit(0)
+    32.0
+    >>> celsius_to_fahrenheit(20)
+    68.0
+    >>> celsius_to_fahrenheit("40")
+    104.0
+    >>> celsius_to_fahrenheit("celsius")
+    Traceback (most recent call last):
+    ...
+    ValueError: could not convert string to float: 'celsius'
+    """
+    return round((float(celsius) * 9 / 5) + 32, 2)
+
+
+def fahrenheit_to_celsius(fahrenheit: float) -> float:
+    """
+    Convert a given value from Fahrenheit to Celsius and round it to 2 decimal places.
+
+    >>> fahrenheit_to_celsius(0)
+    -17.78
+    >>> fahrenheit_to_celsius(20.0)
+    -6.67
+    >>> fahrenheit_to_celsius(40.0)
+    4.44
+    >>> fahrenheit_to_celsius(60)
+    15.56
+    >>> fahrenheit_to_celsius(80)
+    26.67
+    >>> fahrenheit_to_celsius("100")
+    37.78
+    >>> fahrenheit_to_celsius("fahrenheit")
+    Traceback (most recent call last):
+    ...
+    ValueError: could not convert string to float: 'fahrenheit'
+    """
+    return round((float(fahrenheit) - 32) * 5 / 9, 2)
+
+
+def celsius_to_kelvin(celsius: float) -> float:
+    """
+    Convert a given value from Celsius to Kelvin and round it to 2 decimal places.
+
+    >>> celsius_to_kelvin(0)
+    273.15
+    >>> celsius_to_kelvin(20.0)
+    293.15
+    >>> celsius_to_kelvin("40")
+    313.15
+    >>> celsius_to_kelvin("celsius")
+    Traceback (most recent call last):
+    ...
+    ValueError: could not convert string to float: 'celsius'
+    """
+    return round(float(celsius) + 273.15, 2)
+
+
+def kelvin_to_celsius(kelvin: float) -> float:
+    """
+    Convert a given value from Kelvin to Celsius and round it to 2 decimal places.
+
+    >>> kelvin_to_celsius(273.15)
+    0.0
+    >>> kelvin_to_celsius(300)
+    26.85
+    >>> kelvin_to_celsius("315.5")
+    42.35
+    >>> kelvin_to_celsius("kelvin")
+    Traceback (most recent call last):
+    ...
+    ValueError: could not convert string to float: 'kelvin'
+    """
+    return round(float(kelvin) - 273.15, 2)
+
+
+if __name__ == "__main__":
+    import doctest
+    doctest.testmod()