summary.lsp returns a one column data.frame with results from function lsp.  Row names and contents are as follows:
- Time
- Name of the sampling time variable. 
- Data
- Name of the measured variable. 
- Type
- either “frequency” or “period”. 
- Oversampling factor
- The degree of oversampling (>=1). 
- From
- The lowest frequency (or period, depending on type) inspected. 
- To
- The highest frequency (or period, depending on type) inspected. 
- # frequencies
- The number of frequencies (or periods, depending on type) inspected. 
- PNmax
- The peak normalised power in the periodogram. 
- At frequency
- The frequency at which PNmax occurred. 
- At period
- The period at which PNmax occurred. 
- P-value (PNmax)
- The probability that PNmax occurred by chance, computed from the exponential distribution.