Removing characters from a datetime format to make it recognizable to MATLAB

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Aaron DeSantis
Aaron DeSantis 2023-4-8
评论： Peter Perkins 2023-4-10
I have a large data file that includes date information that I would like to convert to a timetable. This is nothing new but the format used by SMT Research is not recognized in Matlab. They use '2022-08-31 16:59:51+00'. The last deliniation remains unused for all data enties, alway '+00' so I would like to remove it. I have atempted to use the erase and replace function but i get the error "First argument must be text." Can someone help with this. Code is below and the imput file and import function are attached.
%% Call imprort function
data = importfileANL("export-4-5-23.csv"); %inputs the specified CSV file as a table
% import function only works with the standard output of Analytics
%% Convert date info from a date string to a datetime array
data = replace(data.DateTime, "+00",""); % removes proprietary millisecond demotation not recognized in matlab
data.DateTime = datetime(data.DateTime,'InputFormat','yyyy-MM-dd HH:mm:ss');

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采纳的回答

Dyuman Joshi
Dyuman Joshi 2023-4-8
Ran in:
The column with date time values is stored as a categorical array. Convert it to a string array and then use replace (you can also use erase)
data = importfileANL("export-4-5-23_shortened.csv");
data.DateTime = replace(string(data.DateTime),"+00","")
data = 16×7 table
DateTime SensorID Name NodeID Input Value EngineeringUnit _____________________ __________ ____________________ ______ _____ __________ _______________ "2022-08-31 16:59:51" 3.7754e+05 New SMT-A2 Sensor 31462 20 1e+09 -2.4977e+05 "2022-08-31 16:59:51" 3.7755e+05 New SMT-A2 Sensor 31462 22 1e+09 -2.4976e+05 "2022-08-31 16:59:51" 3.7754e+05 New SMT-A2 Sensor 31462 21 1e+09 -2.4975e+05 "2022-08-31 16:59:51" 3.7754e+05 Internal Temperature 31462 5 1.13e+05 22.546 "2022-08-31 16:59:51" 3.7754e+05 Internal RH 31462 6 2.4045e+06 59.825 "2022-08-31 16:59:51" 3.7754e+05 Battery 31462 7 4355 4355 "2022-08-31 16:59:51" 3.7754e+05 New SMT-A2 Sensor 31462 17 1e+09 -2.4976e+05 "2022-08-31 16:59:51" 3.7754e+05 New SMT-A2 Sensor 31462 18 1e+09 -2.4976e+05 "2022-08-31 16:59:51" 3.7754e+05 New SMT-A2 Sensor 31462 19 1e+09 -2.4977e+05 "2022-08-31 17:00:37" 3.7754e+05 New SMT-A2 Sensor 31462 17 1e+09 -2.4976e+05 "2022-08-31 17:00:37" 3.7754e+05 New SMT-A2 Sensor 31462 18 1e+09 -2.4976e+05 "2022-08-31 17:00:37" 3.7754e+05 Battery 31462 7 4355 4355 "2022-08-31 17:00:37" 3.7755e+05 New SMT-A2 Sensor 31462 22 1e+09 -2.4976e+05 "2022-08-31 17:00:37" 3.7754e+05 New SMT-A2 Sensor 31462 21 1e+09 -2.4975e+05 "2022-08-31 17:00:37" 3.7754e+05 New SMT-A2 Sensor 31462 20 1e+09 -2.4977e+05 "2022-08-31 17:00:37" 3.7754e+05 New SMT-A2 Sensor 31462 19 1e+09 -2.4977e+05
data.DateTime = datetime(data.DateTime,'InputFormat','yyyy-MM-dd HH:mm:ss')
data = 16×7 table
DateTime SensorID Name NodeID Input Value EngineeringUnit ____________________ __________ ____________________ ______ _____ __________ _______________ 31-Aug-2022 16:59:51 3.7754e+05 New SMT-A2 Sensor 31462 20 1e+09 -2.4977e+05 31-Aug-2022 16:59:51 3.7755e+05 New SMT-A2 Sensor 31462 22 1e+09 -2.4976e+05 31-Aug-2022 16:59:51 3.7754e+05 New SMT-A2 Sensor 31462 21 1e+09 -2.4975e+05 31-Aug-2022 16:59:51 3.7754e+05 Internal Temperature 31462 5 1.13e+05 22.546 31-Aug-2022 16:59:51 3.7754e+05 Internal RH 31462 6 2.4045e+06 59.825 31-Aug-2022 16:59:51 3.7754e+05 Battery 31462 7 4355 4355 31-Aug-2022 16:59:51 3.7754e+05 New SMT-A2 Sensor 31462 17 1e+09 -2.4976e+05 31-Aug-2022 16:59:51 3.7754e+05 New SMT-A2 Sensor 31462 18 1e+09 -2.4976e+05 31-Aug-2022 16:59:51 3.7754e+05 New SMT-A2 Sensor 31462 19 1e+09 -2.4977e+05 31-Aug-2022 17:00:37 3.7754e+05 New SMT-A2 Sensor 31462 17 1e+09 -2.4976e+05 31-Aug-2022 17:00:37 3.7754e+05 New SMT-A2 Sensor 31462 18 1e+09 -2.4976e+05 31-Aug-2022 17:00:37 3.7754e+05 Battery 31462 7 4355 4355 31-Aug-2022 17:00:37 3.7755e+05 New SMT-A2 Sensor 31462 22 1e+09 -2.4976e+05 31-Aug-2022 17:00:37 3.7754e+05 New SMT-A2 Sensor 31462 21 1e+09 -2.4975e+05 31-Aug-2022 17:00:37 3.7754e+05 New SMT-A2 Sensor 31462 20 1e+09 -2.4977e+05 31-Aug-2022 17:00:37 3.7754e+05 New SMT-A2 Sensor 31462 19 1e+09 -2.4977e+05

更多回答（1 个）

Steven Lord
Steven Lord 2023-4-8
Ran in:
You can include literal characters in the InputFormat argument of a call to datetime. See the "Date and Time from Text with Literal Characters" example on the datetime documentation page.
s = '2022-08-31 16:59:51+00'
s = '2022-08-31 16:59:51+00'
d = datetime(s, InputFormat = "yyyy-MM-dd HH:mm:ss+00")
d = datetime
31-Aug-2022 16:59:51
If you want to read in the data with the numbers after the + as the fractional seconds you can do that too.
s = '2022-08-31 16:59:51+79'
s = '2022-08-31 16:59:51+79'
I'll display just the time part of d, but the date part is still present.
d = datetime(s, InputFormat = "yyyy-MM-dd HH:mm:ss+SS", Format = "HH:mm:ss.SS")
d = datetime
16:59:51.79
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Dyuman Joshi
Dyuman Joshi 2023-4-9
@Peter Perkins note that the OP is using their own method to import data, and thus the data for the datetime values is imported as categorical.

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