Speoial character in struct fieldname

Hello,

I have to create structure with fields based on measurements, namely float number:amplitudes = {'0.05', '0.10', '0.15', '0.20', '0.25', '0.30', '0.35',...

'0.40', '0.45', '0.50', '1.00', '1.50', '2.00', '2.50', '3.00',...

'3.50', '4.00', '4.50', '5.00', '5.50' }

How to pass special character "." or "_" in struct field name?

Cheers

E

[Stephen23]

"How to pass special character "." or "_" in struct field name?"

It is not possible to use "." in fieldnames: "Field names can contain ASCII letters (A–Z, a–z), digits (0–9), and underscores, and must begin with a letter". Source:

https://www.mathworks.com/help/matlab/ref/struct.html

Note that rather than converting numeric data to text and then awkwardly force them into dynamic fieldnames you should just store your numeric data as numeric data: possibly a non-scalar struct would be better data design. Or a scalar struct with non-scalar fields. Indexing would be more efficient.

In any case, avoid forcing meta-data into fieldnames.

Answer 1

[Image Analyst]

Have them start with a letter and use underscores instead of dots.

fn = {'v0_05', 'v0_10', 'v0_15', 'v0_20', 'v0_25', 'v0_30', 'v0_35'};
for k = 1 : numel(fn)
    s.(fn{k}) = 0;
end
s

s = struct with fields:
    v0_05: 0
    v0_10: 0
    v0_15: 0
    v0_20: 0
    v0_25: 0
    v0_30: 0
    v0_35: 0

Perhaps you might like to learn about dictionary, though I'd probably use @Stephen23's idea of using a structure array where you just know what index corresponds to each of your floating point values.

help dictionary

--- dictionary not found. Showing help for dictionary instead. ---

 dictionary - Object that maps unique keys to values
    Use a dictionary to efficiently lookup values associated with a key.

    Creation
      Syntax
        d = dictionary(keys,values)
        d = dictionary(k1,v1,...,kN,vN)
        d = dictionary

      Input Arguments
        keys - Keys
          scalar | array
        values - Values
          scalar | array | cell array
        k1,v1,...,kN,vN - Key-value pairs (as separate arguments)
          scalar | array

    Usage
      Syntax
        valueOut = d(keys)
        d(keys) = newValues
        d(keys) = []
        valueOut = d{keys}
        d{keys} = newValues

    Object Functions
      entries      - Key-value pairs of dictionary
      insert       - Add entries to a dictionary
      isConfigured - Determine if dictionary has types assigned to keys and values
      isKey        - Determine if dictionary contains key
      keys         - Keys of dictionary
      lookup       - Find value in dictionary by key
      numEntries   - Number of key-value pairs in dictionary
      remove       - Remove dictionary entries
      types        - Types of dictionary keys and values
      values       - Values of dictionary

    Examples
      openExample('matlab/CreateADictionaryWithSpecifiedKeysAndValuesExample')
      openExample('matlab/StoreHeterogeniousDataInADictionaryExample')
      openExample('matlab/CreateAnEmptyInitializedDictionaryExample')
      openExample('matlab/AddEntriesToAnUnconfiguredDictionaryExample')

    See also configureDictionary, insert, lookup, remove, entries, keys,
      values, types, numEntries, isConfigured, isKey, keyHash, keyMatch

    Introduced in MATLAB in R2022b
    Documentation for dictionary
       doc dictionary

    Folders named dictionary

       datatypes/dictionary    io/dictionary