# entropy: Standard measures of complexity for strings In acss: Algorithmic Complexity for Short Strings

## Description

Functions to compute different measures of complexity for strings: Entropy, Second-Order Entropy, and Change Complexity

## Usage

 ```1 2 3 4 5``` ```entropy(string) entropy2(string) change_complexity(string) ```

## Arguments

 `string` `character` vector containing the to be analyzed strings (can contain multiple strings for the entropy measures).

## Details

For users who need advanced functions, a comprehensive package computing various versions of entropy estimators is available entropy. For users who just need first and second-order entropy and which to apply them to short string, the acss package provides two functions: `entropy` (first-order entropy) and `entropy2` second-order entropy.

Change complexity (`change_complexity`) assesses cognitive complexity or the subjective perception of complexity of a binary string. It has been comprehensively defined by Aksentijevic and Gibson (2012). Although the algorithm will work with any number of symbols up to 10, the rationale of Change Complexity only applies to binary strings.

## Value

`numeric`, the complexity of the string. For `entropy` and `entropy2` of the same length as `string`. `change_complexity` currently only works with inputs of length 1.

## References

Aksentijevic & Gibson (2012). Complexity equals change. Cognitive Systems Research, 15-17, 1-16.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14``` ```strings1 <- c("010011010001", "0010203928837", "0000000000") strings2 <- c("001011", "01213", "010101010101") entropy(strings1) entropy("XYXXYYXYXXXY") # "same" string as strings1[1] entropy(c("HUHHEGGTE", "EGGHHU")) entropy2(strings1) entropy2("XYXXYYXYXXXY") entropy2(strings2) change_complexity(strings1) change_complexity("XYXXYYXYXXXY") ```

### Example output

```Loading required package: acss.data
010011010001 0010203928837    0000000000
0.9798688     2.6235166     0.0000000
XYXXYYXYXXXY
0.9798688
HUHHEGGTE    EGGHHU
2.197160  1.918296
010011010001 0010203928837    0000000000
1.867634      3.584963      0.000000
XYXXYYXYXXXY
1.867634
001011        01213 010101010101
1.9219281    2.0000000    0.9940302
010011010001 0010203928837    0000000000
6.447439      6.443398      0.000000
XYXXYYXYXXXY
6.447439
```

acss documentation built on May 1, 2019, 7:56 p.m.