设$f\left(x\right)$是定义在$R$上的周期为2的函数，当$x\in \left[-1,1\right]$时，$f\left(x\right)=\left\{\begin{array}{l}-4x^2+2,-1\le x\le 0,\\ x,0\le x\le 1,\end{array}\right.$，则$f\left(\frac{3}{2}\right)=$.