Convert a datetime to string
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I want to convert a specific datetime from a table into a string with a certain format, which it also uses in the table. I tried using datestring, with a format for the output : checkdate = datestr(datelist{1,d},'yyyy_MM_dd')
When I use this format for the table I get: 2020_07_17
But when using it with the datestr I get this: '22-Feb-2022'. How can I get the same format from the table as a string?
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Walter Roberson
2023년 11월 23일
The datestr call does produce character vectors based upon a variety of ways of inputting times. However, it is based on an older Mathworks time implementation that Mathworks calls "serial date numbers", which are "number of days and fraction of days since the beginning of year 0 CE." For example,
format long g;
now
so were are currently approaching 3/4 of a million days since the beginning of 0 CE.
The time resolution available with serial date numbers is roughly 10 microseconds.
This is not the only way that MATLAB has of representing time. Mathworks added what it calls "datetime objects" and "duration objects". Datetime objects internally use two double precision objects together, datetime objects have a resolution better than seconds.
If you have a datetime object and you want to convert it to a character vector with a particular format, first set the Format property of the object to the format you want, and then char() or string() the datetime object.
extime = datetime('July 17, 2020 15:43:19')
string(extime)
extime.Format = 'yyyy_MM_dd';
string(extime)
Stephen23
2023년 11월 23일
"I want to convert a specific datetime from a table ... But when using it with the datestr I get this: '22-Feb-2022'"
dt = datetime(2022,2,22) % curiously many 2's
datestr(dt,'yyyy_MM_dd') % does not match what you say you got
If you used DATESTR with that format then there is no way you could get a month abbreviation from uppercase M's.
If you used the correct format (as Alexander Paul showed) then you could:
datestr(dt,'yyyy_mmm_dd') % does not match what you say you did
"When I use this format for the table I get: 2020_07_17"
If the data in the table is not really a DATETIME but really text then note that underscores are not part of any of the supported syntaxes for input date strings. Lets see what happens anyway:
datestr('2022_07_17','yyyy_mmm_dd')
Well, DATESTR seems to have coped with that just fine. Without uploading sample data it is unclear what the problem is.
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Star Strider
2023년 11월 22일
I am not certain what the problem is.
To convert [2022 07 17] to your desired format using datetime, try this —
DT = datetime([2022 07 17], 'Format','yyyy_MM_dd')
To convert it to a string variable:
DTstr = string(DT)
and to a character array:
DTchr = sprintf('%s', DT)
.
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Walter Roberson
2023년 11월 22일
if you have a datetime object then set its Format property. In some cases that is all you need to do; in other cases you need to string() or char() the datetime object afterwards.
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