floating point - Why is NaN not equal to NaN? - Stack Overflow
NaN is designed to propagate through all calculations, infecting them like a virus, so if somewhere in your deep, complex calculations you hit upon a NaN, you don't bubble out a seemingly sensible answer. Otherwise by identity NaN/NaN should equal 1, along with all the other consequences like (NaN/NaN)==1, (NaN*1)==NaN, etc.
math - How to use nan and inf in C? - Stack Overflow
2009年12月18日 — NAN may or may not be defined, and "is defined if and only if the implementation supports quiet NaNs for the float type. It expands to a constant expression of type float representing a quiet NaN." Note that if you're comparing floating point values, and do: a = NAN; even then, a == NAN; is false. One way to check for NaN would be:
python - How to check for NaN values - Stack Overflow
2009年6月3日 — float('nan') represents NaN (not a number). But how do I check for it?
What's the difference between nan, NaN and NAN
2013年7月24日 — Different operating systems and programming languages may have different string representations of NaN: nan NaN NaN% NAN NaNQ NaNS qNaN sNaN 1.#SNAN 1.#QNAN -1.#IND I think having all three is just a convenience. They are the same. >>> np.nan nan >>> np.NaN nan >>> np.NAN nan >>>
How to drop rows of Pandas DataFrame whose value in a certain …
# Setup df = pd.DataFrame({ 'A': [np.nan, 2, 3, 4], 'B': [np.nan, np.nan, 2, 3], 'C': [np.nan]*3 + [3]}) df A B C 0 NaN NaN NaN 1 2.0 NaN NaN 2 3.0 2.0 NaN 3 4.0 3.0 3.0 Below is a detail of the most important arguments and how they work, arranged in an FAQ format.
javascript - Why is NaN === NaN false? - Stack Overflow
Why does NaN === NaN return false in Javascript? > undefined === undefined true > NaN === NaN false > a = NaN NaN > a === a false On the documentation page I see this: Testing against NaN. Equality operator (== and ===) cannot be used to test a value against NaN. Use isNaN instead. Is there any reference that answers to the question? It would ...
Convert Pandas column containing NaNs to dtype `int`
2014年1月22日 — I read data from a .csv file to a Pandas dataframe as below. For one of the columns, namely id, I want to specify the column type as int. The problem is the id series has missing/empty values. Whe...
How do you check that a number is NaN in JavaScript?
2010年4月16日 — To fix the issue where '1.2geoff' becomes parsed, just use the Number() parser instead.. So rather than this: ...
python - How to replace NaNs by preceding or next values in …
>>> example = pd.DataFrame({'number':[0,1,2,nan,4,nan,6,7,8,9],'name':list('aaabbbcccc')}) >>> example ...
r - Why does NaN^0 == 1 - Stack Overflow
2013年7月25日 — NaN preserving and NA preserving work "equivalently" in R, so if you agree that NA^0 should give 1, NaN^0 |-> 1 is a consequence. Indeed (as others said) you should really read R's help pages and not C or IEEE standards, to answer …