Skip to contents

Create AHP pairwise comparison matrix interactively

Source: R/ahp.R
create_ahp_matrix.Rd

This function creates an AHP pairwise comparison matrix through interactive prompts or from a provided matrix. In interactive mode, it guides the user through pairwise comparisons of all indicators, validates inputs, calculates weights, and returns a structured ahp_matrix object.

Usage

create_ahp_matrix(indicators, mode = "interactive", pairwise = NULL)

Arguments

indicators

Character vector of indicator names to be compared.

mode

Character string specifying the mode: "interactive" for guided prompts (default) or "matrix" to provide a pre-built matrix.

pairwise

Optional pre-built pairwise comparison matrix (only used when mode = "matrix"). Must be a square matrix with dimensions matching the number of indicators.

Value

An object of class "ahp_matrix" containing:

indicators

Character vector of indicator names

matrix

Numeric matrix of pairwise comparisons

weights

Named numeric vector of normalized weights

CR

Consistency Ratio

lambda_max

Maximum eigenvalue

Details

In interactive mode, the function displays the Saaty scale and prompts for pairwise comparisons between all indicator pairs. The Saaty scale is:

  • 1 = Equal importance

  • 3 = Moderate importance of first over second

  • 5 = Strong importance of first over second

  • 7 = Very strong importance of first over second

  • 9 = Extreme importance of first over second

  • 2, 4, 6, 8 = Intermediate values

  • 1/3, 1/5, 1/7, 1/9 = Reciprocal values (second more important)

Users can enter values as decimals (e.g., 0.333) or fractions (e.g., "1/3"). The function validates that all inputs are within the valid range (1/9 to 9).

After collecting all comparisons, the function calculates weights using eigenvalue decomposition and computes the Consistency Ratio (CR). If CR > 0.1, a warning is displayed indicating inconsistent judgments.

See also

ahp_weights, ratio_to_saaty

Examples

if (FALSE) { # \dontrun{
# Interactive mode - prompts user for comparisons
ahp_result <- create_ahp_matrix(c("pH", "OM", "P"))
print(ahp_result)
} # }

# Matrix mode - provide pre-built matrix
pairwise <- matrix(c(
  1,   3,   5,
  1/3, 1,   2,
  1/5, 1/2, 1
), nrow = 3, byrow = TRUE)
ahp_result <- create_ahp_matrix(
  indicators = c("pH", "OM", "P"),
  mode = "matrix",
  pairwise = pairwise
)
print(ahp_result)
#> 
#> === AHP Pairwise Comparison Matrix ===
#> 
#> Pairwise Comparison Matrix:
#>       pH  OM P
#> pH 1.000 3.0 5
#> OM 0.333 1.0 2
#> P  0.200 0.5 1
#> 
#> Indicator Weights:
#>   pH             : 0.6483
#>   OM             : 0.2297
#>   P              : 0.1220
#> 
#> Consistency Information:
#>   Lambda Max: 3.0037
#>   Consistency Ratio (CR): 0.0032 [✓ Acceptable]
#>