Error using AHP for R cran.r-project.org/web/packages/ahp

Question

I am using the ahp package for R (cran.r-project.org/web/packages/ahp). I built a new document .ahp with the alternatives and criteria

Version: 2.0

#########################
# Alternatives Section
#

Alternatives: &alternatives
# Here, we list all the alternatives, together with their attributes. 

  A:
    hectareas: 1.88
    ninos: 1
    adultos: 12
  B:
    hectareas: 21.06
    ninos: 14
    adultos: 19


#
# End of Alternatives Section
#####################################

#####################################
# Goal Section
#


Goal:
# The goal spans a tree of criteria and the alternatives
  name: Zona Verde
  description: >
    This is a classic single decision maker problem.
  author: unknown
  preferences:
    # preferences are typically defined pairwise
    # 1 means: A is equal to B
    # 9 means: A is highly preferrable to B
    # 1/9 means: B is highly preferrable to A
    pairwise:
      - [hectareas, ninos, 3]
      - [hectareas, adultos, 7]
      - [ninos, adultos, 3]
  children: 
    hectareas:
      preferences:
        pairwise:
          - [A, B, 9]
        children: *alternatives
    ninos: 
      preferences:
        pairwise:
          - [A, B, 1/3]
        children: *alternatives
    adultos: 
      preferences: 
        pairwise:
          - [A, B, 1/4]
        children: *alternatives
#
# End of Goal Section
#####################################

The other document is ahp.R by te libray and analysis

library(ahp)
#list example files provided by the package
list.files(system.file("extdata", package="ahp"))
#zonas verdes example
ahpFile <- system.file("extdata", "zonasverdes.ahp", package="ahp")
zonasverdesAhp <- Load(ahpFile)
Calculate(zonasverdesAhp)
Analyze(zonasverdesAhp)
AnalyzeTable(zonasverdesAhp)

When I run the code to analyze the AHP results appear this error:

Error in value[[3L]](cond) : 
  Could not load ahp model. Exception caught when converting into a data.tree: Error in preferences[[type]]: attempt to select less than one element in get1index

I do not know if there are mistakes in the code indented or in some functions.

Thanks

Answer 1

This is a question about indentation. In lines 49, 54, and 59 of ahpfile, you need to reduce indentation. like this:

<code>
  children:
    hectareas:
      preferences:
        pairwise:
          - [A, B, 9]
      children: *alternatives
    ninos:
      preferences:
        pairwise:
          - [A, B, 1/3]
      children: *alternatives
    adultos:
      preferences:
        pairwise:
          - [A, B, 1/4]
      children: *alternatives
</code>