nan

问题 I wish to target ARMv6 with VFP Android device. I have following line in my Android.mk file to enable VFP LOCAL_CFLAGS := -marm -mfloat-abi=softfp -mfpu=vfp -Wmultichar I believe I target ARMv5 with VFP . I edited android-ndk-r8b\toolchains\arm-linux-androideabi-4.6\setup.mk to remove -msoft-float . I also tried with original setup.mk My code works fine 99.99% of time but some times goes crazy on ARMv6 devices. I have special code to detect when it goes crazy. Code glm::vec3 D = P1 - P2;

问题 For example: 0 1 0 87.0 NaN 1 NaN 99.0 2 NaN NaN 3 NaN NaN 4 NaN 66.0 5 NaN NaN 6 NaN 77.0 7 NaN NaN 8 NaN NaN 9 88.0 NaN My expected output is: [False, True] since 87 is the first !NaN value but not the maximum in column 0 . 99 however is the first !NaN value and is indeed the max in that column. 回答1: Option a) : Just do groupby with first (May not be 100% reliable ) df.groupby([1]*len(df)).first()==df.max() Out[89]: 0 1 1 False True Option b) : bfill Or using bfill (Fill any NaN value by

问题 In C you can test to see if a double if NaN using isnan(x) . However many places online, including for example this SO answer say that you can simply use x!=x instead. Is x!=x in any C specification as a method that is guaranteed to test if x is NaN? I can't find it myself and I would like my code to work with different compilers. 回答1: Please refer to the normative section Annex F: IEC 60559 floating-point arithmetic of the C standard: F.1 Introduction An implementation that defines __STDC

问题 I have a time series dataframe, the dataframe is quite big and contain some missing values in the 2 columns('Humidity' and 'Pressure'). I would like to impute this missing values in a clever way, for example using the value of the nearest neighbor or the average of the previous and following timestamp.Is there an easy way to do it? I have tried with fancyimpute but the dataset contain around 180000 examples and give a memory error 回答1: Consider interpolate (documentation). This example shows

问题 I'm trying to generate a new column in a pandas DataFrame that equals values in another pandas DataFrame. When I attempt to create the new column I just get NaNs for the new column values. First I use an API call to get some data, and the 'mydata' DataFrame is one column of data indexed by dates mydata = Quandl.get(["YAHOO/INDEX_MXX.4"], trim_start="2001-04-01", trim_end="2014-03-31", collapse="monthly") The next DataFrame I get from a CSV with the following code, and it contains many columns

问题 The gnuplot command set datafile missing "nan" tells gnuplot to ignore nan data values in the data file. How to ignore both nan and -nan ? I tried the following in gnuplot, but then the effect of the first statement is overwritten by the next. gnuplot> set datafile missing "-nan" gnuplot> set datafile missing "nan" Is it possible to somewhow embed a grep -v nan in the gnuplot command, or even some kind of regexp to exclude any imaginable non-numerical data? 回答1: It is not possible to use a

问题 I am calling this line: lang_modifiers = [keyw.strip() for keyw in row["language_modifiers"].split("|") if not isinstance(row["language_modifiers"], float)] This seems to work where row["language_modifiers"] is a word ( atlas method , central ), but not when it comes up as nan . I thought my if not isinstance(row["language_modifiers"], float) could catch the time when things come up as nan but not the case. Background: row["language_modifiers"] is a cell in a tsv file, and comes up as nan

问题 So, the R expression and its output is as follows: > (4-7)^1.3 [1] NaN Any ideas how to solve this in R? 回答1: The answer is a complex number, so you need to give it a complex argument: > (4-7+0i)^1.3 [1] -2.451751-3.374545i but remember this is only one root... 回答2: I quote from Wikipedia, especially the bold text (http://en.wikipedia.org/wiki/Exponentiation): The IEEE 754-2008 floating point standard is used in the design of most > floating point libraries. It recommends a number of

问题 What's the difference between NaN and Infinity ? When does NaN appear? What is it? 回答1: From Wikipedia : In computing, NaN (Not a Number) is a value of the numeric data type representing an undefined or unrepresentable value, especially in floating-point calculations. Systematic use of NaNs was introduced by the IEEE 754 floating-point standard in 1985, along with the representation of other non-finite quantities like infinities. And from MSDN : Represents a value that is not a number (NaN).

问题 C#, VS 2010 I need to determine if a float value is NaN. Testing a float for NaN using float.IsNaN(aFloatNumber) crashes with a stack overflow. So does aFloatNumber.CompareTo(float.NaN). The following does not crash, but it's not useful as it returns NaN regardless: aFloatNumber - float.NaN A search for "stack overflow" returns results about this website instead of results about an actual stack overflow, so I can't find relevant answers. Why is my application going into a stack overflow when