I am trying to learn R and I am having problems with the way it works. I tried to make an entropy function of variables p
and 1-p
from scratch and I am having problems when I try to add some if
s to avoid the NaN
when dividing by 0.
When I try the custom entropy with the plot, it just works but it shows the NaN
when I print the results. But when I try to add the if
s, then it says:
Error in xy.coords(x, y, xlabel, ylabel, log) : 'x' and 'y' lengths differ
entropy <- function(p){
cat("p = " , p)
if (p==0 || p==1) {
result = 0
}else{
result = - p*log2(p)-(1-p)*log2((1-p))
}
cat("\nresult=",result)
return(result)
}
p <- seq(0,1,0.01)
plot(p, entropy(p), type='l', main='Funcion entropia con dos valores posibles')
I don't understand it since I am using a plot of an array as x
and a function with that array as parameter as y
, so it should be the same lengths with and without if
s.
Console without the if
s:
p = 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.2 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.3 0.31 0.32 0.33 0.34 0.35 0.36 0.37 0.38 0.39 0.4 0.41 0.42 0.43 0.44 0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.55 0.56 0.57 0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 0.68 0.69 0.7 0.71 0.72 0.73 0.74 0.75 0.76 0.77 0.78 0.79 0.8 0.81 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.9 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1
result= NaN 0.08079314 0.1414405 0.1943919 0.2422922 0.286397 0.3274449 0.3659237 0.4021792 0.4364698 0.4689956 0.499916 0.5293609 0.5574382 0.5842388 0.6098403 0.6343096 0.6577048 0.680077 0.7014715 0.7219281 0.7414827 0.7601675 0.7780113 0.7950403 0.8112781 0.8267464 0.8414646 0.8554508 0.8687212 0.8812909 0.8931735 0.9043815 0.9149264 0.9248187 0.9340681 0.9426832 0.9506721 0.958042 0.9647995 0.9709506 0.9765005 0.9814539 0.985815 0.9895875 0.9927745 0.9953784 0.9974016 0.9988455 0.9997114 1 0.9997114 0.9988455 0.9974016 0.9953784 0.9927745 0.9895875 0.985815 0.9814539 0.9765005 0.9709506 0.9647995 0.958042 0.9506721 0.9426832 0.9340681 0.9248187 0.9149264 0.9043815 0.8931735 0.8812909 0.8687212 0.8554508 0.8414646 0.8267464 0.8112781 0.7950403 0.7780113 0.7601675 0.7414827 0.7219281 0.7014715 0.680077 0.6577048 0.6343096 0.6098403 0.5842388 0.5574382 0.5293609 0.499916 0.4689956 0.4364698 0.4021792 0.3659237 0.3274449 0.286397 0.2422922 0.1943919 0.1414405 0.08079314 NaN
Console with the if
s:
p = 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.2 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.3 0.31 0.32 0.33 0.34 0.35 0.36 0.37 0.38 0.39 0.4 0.41 0.42 0.43 0.44 0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.55 0.56 0.57 0.58 0.59 0.6 0.61 0.62 0.63 0.64 0.65 0.66 0.67 0.68 0.69 0.7 0.71 0.72 0.73 0.74 0.75 0.76 0.77 0.78 0.79 0.8 0.81 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.9 0.91 0.92 0.93 0.94 0.95 0.96 0.97 0.98 0.99 1 result= 0Error in xy.coords(x, y, xlabel, ylabel, log) : 'x' and 'y' lengths differ