Take string input and reformat as cell array

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Connor Brackley
Connor Brackley 2020-6-10
评论： Connor Brackley 2020-6-10
I would like to convert a string into a cell array. Here is a small example of string:
[{"ts": "2018-07-03T06:30:07", "v": 1.0}, {"ts": "2018-07-03T06:30:12", "v": 0.0}, {"ts": "2018-07-03T08:41:06", "v": 1.0}]
I would like to convert this into the following format:
[ datetime ] [number]
The ts and v refer to timestamp and value, and are not important to keep.
I believe using the textscan is an efficient way to do it, however I cannot figure out how to use it properly, any help is appreciated!

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采纳的回答

Stephen23
Stephen23 2020-6-10
编辑：Stephen23 2020-6-10
>> str = fileread('SampleData.txt');
>> str = regexprep(str,{'",','[":{}\[\]]+'},{' ',''});
>> fmt = '%*s%{yyyy-MM-dd''T''HHmmss}D%*s%f';
>> out = textscan(str,fmt,'EndOfLine',',');
Checking the output:
>> out{1}
ans =
2018-07-01T101102
2018-07-01T101107
2018-07-01T101109
2018-07-01T101114
2018-07-01T101120
2018-07-01T101125
etc.
  2 个评论
Stephen23
Stephen23 2020-6-10
Do you have any control over the file format?
If it was possible to change the character between each set of {...} (e.g. to ';' or similar) then it would be possible to use textscan directly on the file itself, which would likely be much faster.
Connor Brackley
Connor Brackley 2020-6-10
No, this format is direclty from an API of a service being used to store the data. For my purposes this is fast enough, but thank you for trying to improve it.

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更多回答（1 个）

Ameer Hamza
Ameer Hamza 2020-6-10
编辑：Ameer Hamza 2020-6-10
Try this
str = fileread('test.txt');
dts = regexp(str, '"ts": "([0-9:T-]*)"', 'tokens');
vs = regexp(str, '"v": ([0-9.]*)', 'tokens');
dts = cellfun(@(x) datetime(x, 'InputFormat', 'yyyy-MM-dd''T''HH:mm:ss'), [dts{:}]);
vs = cellfun(@str2double, [vs{:}]);
T = table(dts.', vs.', 'VariableNames', {'DateTime', 'V'});
disp(T)
Result
DateTime V
____________________ _
03-Jul-2018 06:30:07 1
03-Jul-2018 06:30:12 0
03-Jul-2018 08:41:06 1
  1 个评论
Connor Brackley
Connor Brackley 2020-6-10
Thank you! This worked, however @Stephen Cobeldick's answer performed the task much faster. I had 400,000+ datapoints to process so speed was important :)

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