Notes

Data types

Fortran namelists do not contain any information about data type, which is determined by the target variables of the Fortran executable. f90nml infers the data type based on the value, but not all cases can be explicitly resolved.

f90nml tests values as one of each data type in the order listed below:

• Integer

• Floating point

• Complex floating point

• Logical (boolean)

• String

Strings act as a fallback type. If a value cannot be matched to any other value, then it is interpreted as a string.

In order to get the best results from f90nml, it is best to follow these guidelines:

• All strings should be enclosed by string delimiters (', ").

• Floating point values should use decimals (.) or E notation.

• Array indices should be explicit

• Array values should be separated by commas (,)

Derived Types

User-defined types are saved as a nested hierarchy of dicts. For example, the following namelist

&dtype_nml
   a%b%c = 1
/

would be saved as the following Namelist:

nml = {
   'dtype_nml': {
      'a': {
         'b': {
            'c': 1
         }
      }
   }
}

Indexing

The indexing of a vector is defined in the Fortran source file, and a namelist can produce unexpected results if the starting index is implicit or unspecified. For example, the namelist below

&idx_nml
   v(1:2) = 5, 5
/

will assign values to different indices of v depending on its starting index, as in the examples below.

integer, dimension :: v(1:4)  ! Read as v = (5, 5, -, -)
integer, dimension :: v(0:3)  ! Read as v = (-, 5, 5, -)

Without explicit knowledge of the starting index, it is not possible to unambiguously represent the vector in Python.

In most cases, f90nml will internally assume a 1-based indexing, and will only output the values explicitly listed in the namelist file. If no index is provided, then f90nml will not add indices to the record.

However, f90nml can still provide some level of control over the starting index of a vector. The starting index can be explicitly set using various properties defined in the Parser and Namelist objects. For more information, see the class API.