How to get approximation coeff. Of WT of all levels

Question

I am running a WT using pywt.wavedec on a gait signal (accelerometer and gyroscope data), I'm setting level to 5 and using a db4 Wavelet. I am wondering why we only get the approximation coefficient cAn (cA5 in my case) returned from the pywt function. How do I access the rest of the approximation coefficients? Would appreciate the help, thank you!

Answer 1

Basically at level 5, cA4 decomposition on one level yields cA5 and cD5. This applies to all levels. Hence, you have all information for cA4 if you recompose one wavelet level from cA5 and cD5.