polyfit returns NaN values in p
72 次查看(过去 30 天)
显示 更早的评论
I want to do a linear regression on the response Y (attached)with a predictor vector X. Therefore, I used Matlab polyfit function: [p,s,mu]=polyfit(X,Y,1) but it returns p=[NaN,Inf]
I have Inf values in vector Y. Is it the cause?
0 个评论
采纳的回答
John D'Errico
2015-5-18
编辑:John D'Errico
2015-5-18
Yes. infs in your data will surely cause NaNs, and essentially garbage results. Drop them out first if you expect something meaningful.
y = [rand(10,1);inf];
x = rand(11,1);
p = polyfit(x,y,1)
p =
NaN Inf
Surely you don't expect anything reasonable to come out of such a computation with INFs in it. What would the slope of such a line be with some data points at infinity? Of course, any such point at infinity would have infinite leverage.
0 个评论
更多回答(1 个)
carlo lefevre
2015-12-9
ind = 1:length(a); k = ~isnan(a); p = polyfit(ind(k),a(k),n)
1 个评论
Steven Lord
2015-12-9
You probably want to use ISFINITE instead of ~ISNAN to include only finite values (excluding Inf, -Inf, and NaN) rather than including only non-NaN values (which would NOT exclude Inf or -Inf.)
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Logical 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!