nan

Why is `null + 1 = 1` but `undefined + 1 = NaN`?

由 喜你入骨 提交于 2019-12-02 00:16:33
问题 null + 1 = 1 undefined + 1 = NaN I am not able to understand what is the logic behind this. Shouldn't both have returned same result? 回答1: Basically, because that's what the language spec says - looking at ToNumber: Type Result Null +0 Undefined NaN And NaN + anything is NaN This might make some sense from the language perspective: null means an explicit empty value whereas undefined implies an unknown value. In some way - zero is the "number empty value" since it is neutral to addition. That

Is there a way to remove nan from a dictionary filled with data?

由 旧城冷巷雨未停 提交于 2019-12-01 18:17:08
I have a dictionary that is filled with data from two files I imported, but some of the data comes out as nan. How do I remove the pieces of data with nan? My code is: import matplotlib.pyplot as plt from pandas.lib import Timestamp import numpy as np from datetime import datetime import pandas as pd import collections orangebook = pd.read_csv('C:\Users\WEGWEIS_JAKE\Desktop\Work Programs\Code Files\products2.txt',sep='~', parse_dates=['Approval_Date']) specificdrugs=pd.read_csv('C:\Users\WEGWEIS_JAKE\Desktop\Work Programs\Code Files\Drugs.txt',sep=',') """This is a dictionary that collects

R cor returns NaN sometimes

由 我只是一个虾纸丫 提交于 2019-12-01 17:38:47
I've been working on some data, available here: Dropbox' csv file (please be kind to use it to replicate the error). When I run the code: t<-read.csv("120.csv") x<-NULL for (i in 1:100){ x<-c(x,cor(t$nitrate,t$sulfate,use="na.or.complete")) } sum(is.nan(x)) I get random values of the last expression, usually around 55 to 60. I expect cor to give repetible results, so I expect x to be a vector of length=100 made of identical values. See, for example, the output of two independent runs: > x<-NULL; for (i in 1:100){x<-c(x,cor(t$nitrate,t$sulfate,use="na.or.complete"))} > sum(is.nan(x)) [1] 62 >

Is there a way to remove nan from a dictionary filled with data?

由 点点圈 提交于 2019-12-01 16:26:47
问题 I have a dictionary that is filled with data from two files I imported, but some of the data comes out as nan. How do I remove the pieces of data with nan? My code is: import matplotlib.pyplot as plt from pandas.lib import Timestamp import numpy as np from datetime import datetime import pandas as pd import collections orangebook = pd.read_csv('C:\Users\WEGWEIS_JAKE\Desktop\Work Programs\Code Files\products2.txt',sep='~', parse_dates=['Approval_Date']) specificdrugs=pd.read_csv('C:\Users

How to change NaN string representation in C#?

由 邮差的信 提交于 2019-12-01 16:22:19
My program saves a pointcloud to file, where each pointcloud is a Point3D[,] , from the System.Windows.Media.Media3D namespace. This shows a line of the output file (in portuguese): -112,644088741971;71,796623005014;NaN (Não é um número) while I'd like it to be (on order to be correctly parsed afterwards): -112,644088741971;71,796623005014;NaN The block of code that generates the file is here: var lines = new List<string>(); for (int rows = 0; rows < malha.GetLength(0); rows++) { for (int cols = 0; cols < malha.GetLength(1); cols++) { double x = coordenadas_x[cols]; double y = coordenadas_y

How to check if value is nan in unittest?

由 二次信任 提交于 2019-12-01 15:47:27
I've got functions, which sometimes return NaNs with float('nan') (I'm not using numpy). How do I write a test for it, since assertEqual(nan_value, float('nan')) is just like float('nan') == float('nan') always false. Is there maybe something like assertIsNan ? I could not find anything about it… I came up with assertTrue(math.isnan(nan_value)) math.isnan(x) will raise a TypeError if x is neither a float nor a Real . It's better to use something like this : import math class NumericAssertions: """ This class is following the UnitTest naming conventions. It is meant to be used along with

Problems casting NAN floats to int

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-01 15:19:54
Ignoring why I would want to do this, the 754 IEEE fp standard doesn't define the behavior for the following: float h = NAN; printf("%x %d\n", (int)h, (int)h); Gives: 80000000 -2147483648 Basically, regardless of what value of NAN I give, it outputs 80000000 (hex) or -2147483648 (dec). Is there a reason for this and/or is this correct behavior? If so, how come? The way I'm giving it different values of NaN are here: How can I manually set the bit value of a float that equates to NaN? So basically, are there cases where the payload of the NaN affects the output of the cast? Thanks! The result

PHP returning NaN

由 。_饼干妹妹 提交于 2019-12-01 14:23:14
问题 I have a function that calculates the distance between two GPS coordinates. I then get all the coordinates from the database and loop through them all to get the distance between the current one and the previous one, then add that to an array for the specific GPS device. For some reason it is return NaN. I have tried casting it as a double, an int, and rounding the number. Here is my PHP code: function distance($lat1, $lon1, $lat2, $lon2) { $lat1 = round($lat1, 3); $lon1 = round($lon1, 3);

Problems casting NAN floats to int

由 南楼画角 提交于 2019-12-01 14:08:50
问题 Ignoring why I would want to do this, the 754 IEEE fp standard doesn't define the behavior for the following: float h = NAN; printf("%x %d\n", (int)h, (int)h); Gives: 80000000 -2147483648 Basically, regardless of what value of NAN I give, it outputs 80000000 (hex) or -2147483648 (dec). Is there a reason for this and/or is this correct behavior? If so, how come? The way I'm giving it different values of NaN are here: How can I manually set the bit value of a float that equates to NaN? So

How to check if value is nan in unittest?

由 风格不统一 提交于 2019-12-01 13:53:51
问题 I've got functions, which sometimes return NaNs with float('nan') (I'm not using numpy). How do I write a test for it, since assertEqual(nan_value, float('nan')) is just like float('nan') == float('nan') always false. Is there maybe something like assertIsNan ? I could not find anything about it… 回答1: I came up with assertTrue(math.isnan(nan_value)) 回答2: math.isnan(x) will raise a TypeError if x is neither a float nor a Real . It's better to use something like this : import math class
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