Change date InputFormat across a cell

Dear all,

How to change datetime format of this attached cell arrays from 1/1/1989 to 1989-1-1?

Here is my try, but it doesnt worked:

d = cellfun(@(OBS_MAX) datetime(OBS_MAX, 'InputFormat', 'yyyy-MM-dd'), OBS_MAX, 'UniformOutput', false);

Thank you all in advanced.

Answer 1

[Voss]

load('OBS_MAX.mat')

OBS_MAX = cellfun(@set_dates_format,OBS_MAX,'UniformOutput',false);

function t = set_dates_format(t)
t.dates.Format = 'yyyy-MM-dd';
end

Answer 2

[Walter Roberson]

You do not have a cell array of datetime objects: you have a cell array of tables, and you need to affect one particular variable inside the table. This is difficult to do without a helper function, but not difficult if you use a helper function.

d = cellfun(@bashdatesformat, OBS_MAX, 'uniform', 0)

function newT = bashdatesformat(T)
   T.dates.Format = 'yyyy-MM-dd');
end

Without the helper function, it gets... messy... involving pulling apart tables and putting them back together into new tables. One might have hopes that you could at least do

cellfun(@(V) subsasgn(V, substruct('.', 'dates', '.', 'Format'), 'yyyy-MM-dd'), C, 'uniform', 0)

but that does not work in practice for this particular case. (It is a trick that can work for some other kinds of variables; see https://www.mathworks.com/matlabcentral/answers/440856-replacing-nans-with-zero-in-a-matrix-within-a-cell-array#answer_357449 )