MATLAB: Preallocating a structure with fieldnames in the form of a string from another structure

function inputstringstruct

say i have a nested structure called tire
 tire = 
  struct with fields:
    lat: [1×1 struct]
    cmb: [1×1 struct]
 tire.lat=
  struct with fields:
      p8: [1×1 struct]
     p10: [1×1 struct]
     p12: [1×1 struct]
     p14: [1×1 struct]
    p12i: [1×1 struct]
I had previously manually entered:
fy_offsets=struct('p8',[],'p10',[],'p12',[],'p14',[],'p12i',[])
fy_offsets = 
struct with fields:
    p8: []
   p10: []
   p12: []
   p14: []
  p12i: []
In order to create an empty struct to fill with data from later processing but want it automated and self forming. I used the following code:
ps=fieldnames(tire.lat); %which pressures do we have in fields tire.lat
p=ps';  %designated pressures in cell vector for new struct fieldnames
p_str=strjoin(ps,"',[],'") %adds ,[], between every entry in string
str_begin=("'")  %places ' at the leading position
str_end=("',[]")  %places ,[] at the end of the string
p_input=strcat(str_begin,p_str,str_end) %concatnates the strings into one string with one entry  "'p8',[],'p10',[],'p12',[],'p14',[],'p12i',[]"
fy_offsets=struct(p_input)                      %tries to create struct with empty fields for filling
Outputs are as follows:
 ps =
  5×1 cell array
    {'p8'  }
    {'p10' }
    {'p12' }
    {'p14' }
    {'p12i'}
 p =
  1×5 cell array
    {'p8'}    {'p10'}    {'p12'}    {'p14'}    {'p12i'}
 p_input = 
    "'p8',[],'p10',[],'p12',[],'p14',[],'p12i',[]"
 fy_offsets=struct(p_input) 
 Error using struct
 Conversion to struct from string is not possible.
Is there a way to get the struct function to accept this input?

Best Answer

Don't use strings and don't think about eval. This could be done with colon expansion and a cell array to produce a comma separated list for the call to struct (exercise for reader or I can follow up later if your stuck) or with cell2struct:
ps=fieldnames(tire.lat);
newstruct=cell2struct(cell(numel(ps),1),ps);
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