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Fisher's natural breaks classification

Source: R/fisher_classify.R
fisher_classify.Rd

Classifies a continuous numeric vector into intervals using Fisher-Jenks natural breaks. Useful for choropleth mapping or other applications where grouped ranges are required.

Usage

fisher_classify(vec, n = 7, diglab = 2)

fisher(vec, n = 7, diglab = 2)

Arguments

vec

A numeric vector to be classified.

n

Integer. Number of classes to generate (default = 7).

diglab

Integer. Number of significant digits to use for labels (default = 2).

Value

A factor with class intervals as levels.

Details

The "fisher" style uses the algorithm proposed by W. D. Fisher (1958) and discussed by Slocum et al. (2005) as the Fisher-Jenks algorithm. This function is a wrapper around the classInt package.

References

Bivand, R. (2018). classInt: Choose Univariate Class Intervals. R package version 0.2-3. https://CRAN.R-project.org/package=classInt

Fisher, W. D. (1958). On grouping for maximum homogeneity. Journal of the American Statistical Association, 53, pp. 789–798. doi:10.1080/01621459.1958.10501479

Author

Martin Haringa

Examples

set.seed(1)
x <- rnorm(100)
fisher_classify(x, n = 5)
#>   [1] (-1.1,-0.34] (-0.34,0.23] (-1.1,-0.34] (1,2.4]      (0.23,1]    
#>   [6] (-1.1,-0.34] (0.23,1]     (0.23,1]     (0.23,1]     (-0.34,0.23]
#>  [11] (1,2.4]      (0.23,1]     (-1.1,-0.34] [-2.2,-1.1]  (1,2.4]     
#>  [16] (-0.34,0.23] (-0.34,0.23] (0.23,1]     (0.23,1]     (0.23,1]    
#>  [21] (0.23,1]     (0.23,1]     (-0.34,0.23] [-2.2,-1.1]  (0.23,1]    
#>  [26] (-0.34,0.23] (-0.34,0.23] [-2.2,-1.1]  (-1.1,-0.34] (0.23,1]    
#>  [31] (1,2.4]      (-0.34,0.23] (0.23,1]     (-0.34,0.23] [-2.2,-1.1] 
#>  [36] (-1.1,-0.34] (-1.1,-0.34] (-0.34,0.23] (1,2.4]      (0.23,1]    
#>  [41] (-0.34,0.23] (-0.34,0.23] (0.23,1]     (0.23,1]     (-1.1,-0.34]
#>  [46] (-1.1,-0.34] (0.23,1]     (0.23,1]     (-0.34,0.23] (0.23,1]    
#>  [51] (0.23,1]     (-1.1,-0.34] (0.23,1]     [-2.2,-1.1]  (1,2.4]     
#>  [56] (1,2.4]      (-1.1,-0.34] (-1.1,-0.34] (0.23,1]     (-0.34,0.23]
#>  [61] (1,2.4]      (-0.34,0.23] (0.23,1]     (-0.34,0.23] (-1.1,-0.34]
#>  [66] (-0.34,0.23] [-2.2,-1.1]  (1,2.4]      (-0.34,0.23] (1,2.4]     
#>  [71] (0.23,1]     (-1.1,-0.34] (0.23,1]     (-1.1,-0.34] [-2.2,-1.1] 
#>  [76] (0.23,1]     (-1.1,-0.34] (-0.34,0.23] (-0.34,0.23] (-1.1,-0.34]
#>  [81] (-1.1,-0.34] (-0.34,0.23] (1,2.4]      [-2.2,-1.1]  (0.23,1]    
#>  [86] (0.23,1]     (1,2.4]      (-0.34,0.23] (0.23,1]     (0.23,1]    
#>  [91] (-1.1,-0.34] (1,2.4]      (1,2.4]      (0.23,1]     (1,2.4]     
#>  [96] (0.23,1]     [-2.2,-1.1]  (-1.1,-0.34] [-2.2,-1.1]  (-1.1,-0.34]
#> Levels: [-2.2,-1.1] (-1.1,-0.34] (-0.34,0.23] (0.23,1] (1,2.4]