# comp_prob_freq

##### Compute probabilities from (4 essential) frequencies.

`comp_prob_freq`

computes current probability information
from 4 essential frequencies
(`hi`

, `mi`

, `fa`

, `cr`

).
It returns a list of 11 frequencies `freq`

for a population of `N`

individuals
as its output.

##### Usage

```
comp_prob_freq(hi = freq$hi, mi = freq$mi, fa = freq$fa,
cr = freq$cr)
```

##### Arguments

##### Details

Key relationships between frequencies and probabilities
(see documentation of `comp_freq`

or `comp_prob`

for details):

Three perspectives on a population:

by condition / by decision / by accuracy.

Defining probabilities in terms of frequencies:

Probabilities can be computed as ratios between frequencies, but beware of rounding issues.

Functions translating between representational formats:
`comp_prob_prob`

, `comp_prob_freq`

,
`comp_freq_prob`

, `comp_freq_freq`

(see documentation of `comp_prob_prob`

for details).

##### See Also

`comp_freq_freq`

computes current frequency information from (4 essential) frequencies;
`comp_freq_prob`

computes current frequency information from (3 essential) probabilities;
`comp_prob_prob`

computes current probability information from (3 essential) probabilities;
`num`

contains basic numeric parameters;
`init_num`

initializes basic numeric parameters;
`prob`

contains current probability information;
`comp_prob`

computes current probability information;
`freq`

contains current frequency information;
`comp_freq`

computes current frequency information;
`is_prob`

verifies probability inputs;
`is_freq`

verifies frequency inputs.

Other functions computing probabilities: `comp_FDR`

,
`comp_FOR`

, `comp_NPV`

,
`comp_PPV`

, `comp_accu_freq`

,
`comp_accu_prob`

, `comp_acc`

,
`comp_comp_pair`

,
`comp_complement`

,
`comp_complete_prob_set`

,
`comp_err`

, `comp_fart`

,
`comp_mirt`

, `comp_ppod`

,
`comp_prob`

, `comp_sens`

,
`comp_spec`

Other format conversion functions: `comp_freq_freq`

,
`comp_freq_prob`

,
`comp_prob_prob`

##### Examples

```
# NOT RUN {
## Basics:
comp_prob_freq() # => computes prob from current freq
## Beware of rounding:
all.equal(prob, comp_prob_freq()) # => would be TRUE (IF freq were NOT rounded)!
fe <- comp_freq(round = FALSE) # compute exact freq (not rounded)
all.equal(prob, comp_prob_freq(fe$hi, fe$mi, fe$fa, fe$cr)) # is TRUE (qed).
## Explain by circular chain (compute prob 1. from num and 2. from freq)
# 0. Inspect current numeric parameters:
num
# 1. Compute currently 11 probabilities in prob (from essential probabilities):
prob <- comp_prob()
prob
# 2. Compute currently 11 frequencies in freq (from essential probabilities):
freq <- comp_freq(round = FALSE) # no rounding (to obtain same probabilities later)
freq
# 3. Compute currently 11 probabilities again (but now from frequencies):
prob_freq <- comp_prob_freq()
prob_freq
# 4. Check equality of probabilities (in steps 1. and 3.):
all.equal(prob, prob_freq) # => should be TRUE!
# }
```

*Documentation reproduced from package riskyr, version 0.2.0, License: GPL-2 | GPL-3*