Price Relative Strength (PRS)

get_prs(eval_history, base_history, lookback_periods=None, sma_periods=None)

Parameters

name	type	notes
`eval_history`	Iterable[Quote]	Historical quotes for evaluation. You must have the same number of periods as `base_history`. • See here for usage with pandas.DataFrame
`base_history`	Iterable[Quote]	Iterable of the Quote class or its sub-class.
`lookback_periods`	int, Optional	Number of periods (`N`) to lookback to compute % difference. Must be greater than 0 if specified or `None`.
`sma_periods`	int, Optional	Number of periods (`S`) in the SMA lookback period for `prs`. Must be greater than 0.

Historical quotes requirements

You must have at least N periods of base_history to calculate prs_percent if lookback_periods is specified; otherwise, you must specify at least S+1 periods. More than the minimum is typically specified. For this indicator, the elements must match (e.g. the nth elements must be the same date). An Exception will be thrown for mismatch dates. Historical price quotes should have a consistent frequency (day, hour, minute, etc).

base_history is an Iterable[Quote] collection of historical price quotes. It should have a consistent frequency (day, hour, minute, etc). See the Guide for more information.

Return

PRSResults[PRSResult]

This method returns a time series of all available indicator values for the quotes provided.
PRSResults is just a list of PRSResult.
It always returns the same number of elements as there are in the historical quotes.
It does not return a single incremental indicator value.
The N periods will have None values for prs_percent and the first S-1 periods will have None values for sma since there’s not enough data to calculate.

PRSResult

name	type	notes
`date`	datetime	Date
`prs`	float, Optional	Price Relative Strength compares `eval_history` to `base_history`
`prs_sma`	float, Optional	Moving Average (SMA) of PRS over `S` periods
`prs_percent`	float, Optional	Percent change difference between `eval_history` and `base_history` over `N` periods

Utilities

See Utilities and Helpers for more information.

Example

from stock_indicators import indicators

# This method is NOT a part of the library.
history_SPX = get_historical_quotes("SPX")
history_TSLA = get_historical_quotes("TSLA")

# Calculate 14-period PRS
results = indicators.get_prs(history_SPX, history_TSLA, 14)

About Price Relative Strength (PRS)

Price Relative Strength (PRS), also called Comparative Relative Strength, shows the ratio of two quote histories, based on Close price. It is often used to compare against a market index or sector ETF. When using the optional lookback_periods, this also returns relative percent change over the specified periods. This is not the same as the more prevalent Relative Strength Index (RSI). [Discuss] 💬