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how to read selected data from text file matlab ?

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pruth
pruth on 16 Aug 2018
Edited: pruth on 17 Aug 2018
hi, I have this text file. (attached).
from this text file I only want read only second column(date), third column(time) and the last column. first 11 rows can be deleted. since time and date are two different column I am not able to combine them and make single vector. I just want do hourly average which I can do for sure. but I can not read and collect the data from this file in the first place. I Hope you understand my question. thanks

Accepted Answer

jonas
jonas on 16 Aug 2018
Edited: jonas on 16 Aug 2018
readtable can do this for you easily.
%%Read the relevant columns, exclude 10 rows
opts=detectImportOptions('str.txt','NumHeaderLines',10);
opts.SelectedVariableNames = {'timestamp','RPM','absE_f'};
opts = setvartype(opts,{'timestamp','RPM'},{'datetime','duration'})
T=readtable('str.txt',opts)
t=T.timestamp+T.RPM;
readtable automatically detects the datetime and duration format of columns 2 and 3. If it fails, you can specify the format in detectImportOptions. Now, just build a timetable:
TT=timetable(t,T.absE_f)
ans =
10×1 timetable
t Var1
____________________ ________
02-Jan-2006 00:00:00 131.96
02-Jan-2006 00:00:10 -0.26753
02-Jan-2006 00:00:20 -0.29573
02-Jan-2006 00:00:30 127.73
Finally,
TT2 = retime(TT,'hourly','mean')
  16 Comments
jonas
jonas on 17 Aug 2018
Yes sorry, my bad. Grab the time by
datenum(TT.t)
No problem! Happy to help.

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More Answers (1)

pruth
pruth on 17 Aug 2018
Edited: pruth on 17 Aug 2018
final code. !!
clear all
close all
clc
opts=detectImportOptions('2jan.txt','NumHeaderLines',10); %%%Read the relevant columns, exclude 10 rows
opts.SelectedVariableNames = {'timestamp','RPM','absE_f'};
opts = setvartype(opts,'timestamp','datetime');
opts = setvartype(opts,'RPM','datetime');
opts = setvaropts(opts,'timestamp','InputFormat','MM/dd/yyyy');
opts = setvaropts(opts,'RPM','InputFormat','HH:mm:SS');
T=readtable('2jan.txt',opts);
Date=datetime(T.timestamp,'format','yyyy-MM-dd hh:mm:SS');
TimeOfDay=hours(hour(T.RPM))+minutes(minute(T.RPM))+seconds(second(T.RPM));
t=Date+TimeOfDay;
TT=timetable(t,T.absE_f);
TT2 = retime(TT,'hourly','mean');
final(:,1)=datenum(TT2.t(:,1));
final(:,2)= TT2.Var1(:,1);

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