igo-dyadic.md
In igoR: Access the Intergovernmental Organizations ('IGO') Database

non-numeric years return NULL with a warning

Code
  n <- igo_dyadic("USA", "CUBA", year = NULL)
Condition
  Warning in `igo_dyadic()`:
  `year` must be numeric, not NULL.

unsupported numeric years return NULL with a warning

Code
  res <- igo_dyadic("USA", "Spain", c(NA, NaN, Inf, 1990.5), "UN")
Message
  No IGO records were found for the selected years.
Condition
  Warning in `igo_dyadic()`:
  No dyad-year results were found for the supplied arguments.

empty year vectors return NULL with a warning

Code
  res <- igo_dyadic("USA", "Spain", numeric(), "UN")
Message
  No IGO records were found for the selected years.
Condition
  Warning in `igo_dyadic()`:
  No dyad-year results were found for the supplied arguments.

state pairs outside the state system return NULL

Code
  n <- igo_dyadic("USA", "Cuba", 1900)
Message
  State 'cuba' was not in the state system in the selected years.
Condition
  Warning in `igo_dyadic()`:
  No dyad-year results were found for the supplied arguments.

self-pairs return NULL

Code
  n <- igo_dyadic("USA", "USA")
Condition
  Warning in `igo_dyadic()`:
  No distinct states were found between `country1` and `country2`.

unknown IGO names return NULL

Code
  n <- igo_dyadic("USA", "Cuba", ioname = "Not an IGO")
Message
  Unknown values for `ioname`: 'not an igo'.
Condition
  Warning in `igo_dyadic()`:
  No dyad-year results were found for the supplied arguments.

unknown states return NULL

Code
  n <- igo_dyadic("Not a country", "banana", 1900)
Message
  Unknown value for `state`: 'Not a country'.
  Unknown value for `state`: 'banana'.
Condition
  Warning in `igo_dyadic()`:
  No valid states were found for comparison.

partially unavailable state pairs return NULL

Code
  n <- igo_dyadic("Cuba", "USa", 1900)
Message
  State 'cuba' was not in the state system in the selected years.
Condition
  Warning in `igo_dyadic()`:
  No dyad-year results were found for the supplied arguments.

years outside the IGO data return NULL

Code
  n <- igo_dyadic("France", "Spain", 2200)
Message
  No IGO records were found for the selected years.
Condition
  Warning in `igo_dyadic()`:
  No dyad-year results were found for the supplied arguments.