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How do I Subscript Duration Row times with Date Time values?

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Xel Ch
Xel Ch 2018-6-19
回答： Peter Perkins 2018-7-5
Hello,
I am plotting some data from a .csv file, one year at a time. When I select a certain time range, I am given the error, "A timetable with duration row times cannot be subscripted using datetime values."
I am attaching the code below, and it says the error is in the sixth line (TT2 = TT(TR,6);). Any help is appreciated, thanks!
[
T = readtable('QuakeTrials.csv');
TT = table2timetable(T);
TT(3:7,:)
TR = timerange('2017-01-01','2017-12-31');
TT2 = TT(TR,6);
TT2(3:7,:)

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回答（5 个）

Xel Ch
Xel Ch 2018-6-19
Sure, this should be it, thanks in advance!
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Xel Ch
Xel Ch 2018-6-19
Just deleted the time data in my table because it is irrelevant to what I am trying to do right now, and fixed format of my code so that it catches everything. Here is the cleaned up version of my file and code if it is easier to work with. After running it this way, I am now getting the error, "Row index exceeds table dimensions" on line 7 (last line of the code).
T = readtable('QuakeTrials.csv');
TT = table2timetable(T);
TT(3:7,:)
TR = timerange('2017:01:01','2017:12:30');
TT2 = TT(TR,6);
TT2(4:8,:)
Paolo
Paolo 2018-6-19
Right, I am assuming that '2017:01:01' is 'yyyy:mm:dd'. I have submitted an answer for the updated QuakeTrials.csv below, hope that it solves the problem.

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Walter Roberson
Walter Roberson 2018-6-19
编辑：Walter Roberson 2018-6-19
T = readtable('QuakeTrials.csv');
T = T(3:end,:);
dt = datetime(T{:,1}, T{:,2}, T{:,3}) + T{:,4};
TT = table2timetable(T, 'rowtimes', dt);
TR = timerange('2017-01-01','2017-12-31');
TT_lat = TT(TR,6)
  1 个评论
Walter Roberson
Walter Roberson 2018-6-19
In R2018a the above code produces
TT_lat =
3×1 timetable
Time Latitude
____________________ ________
02-Jan-2017 23:18:23 46.59
03-Jan-2017 04:17:25 45.81
06-Jan-2017 05:03:17 45.13
In earlier versions you might need to do
filename = 'QuakeTrials.csv';
opt = detectImportOptions(filename);
opt = setvartype(opt, 4, 'datetime');
T = readtable(filename, opt);
%do not subselect T(3:end,:) here as detectImportOptions already skips it
dt = datetime(T{:,1}, T{:,2}, T{:,3}) + (T{:,4} - dateshift(T{:,4},'start','day'));
TT = table2timetable(T, 'rowtimes', dt);
TR = timerange('2017-01-01','2017-12-31');
TT_lat = TT(TR,6)
Tested in R2017b.

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Paolo
Paolo 2018-6-19
编辑：Paolo 2018-6-19
opts = detectImportOptions('QuakeTrials.csv');
opts.MissingRule = 'omitvar';
T = readtable('QuakeTrials.csv',opts);
T.Date = cellfun(@(x) datetime(x,'InputFormat','yyyy:mm:dd','Format','dd/mm/yyyy'),T.Date);
TT = table2timetable(T);
TR = timerange('01/02/2017','30/12/2017');
TT2 = TT(TR,6);
TT2 =
3×1 timetable
Date Var13
__________ _____
02/01/2017 1.6
03/01/2017 2.1
06/01/2017 1.4
Xel Ch
Xel Ch 2018-6-19
Hi Paolo, thanks for the suggestion. I am still getting an error on the line starting with "T.Date", which says
Error using cellfun
Input #2 expected to be a cell array, was duration instead.
Any tips for getting through this?
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Paolo
Paolo 2018-6-19
@Walter The behavior for readtable must have changed then because I am unable to run your solution. T{:,2} and T{:,3} are in fact NaN.
Error in game (line 266)
dt = datetime(T{:,1}, T{:,2}, T{:,3}) + T{:,4};
Parameter name must be text.
@Alexander You can place a breakpoint by clicking on the gray vertical line of the editor, a red circle will appear. Yes, T.Date is definitely of type duration. Have you tried using the solution proposed by Walter?
Alternatively you can try:
T.Date = char(duration(T.Date,'Format','hh:mm:ss'))
T.Date = datetime(T.Date,'InputFormat','yyyy:mm:dd','Format','dd/mm/yyyy')

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Peter Perkins
Peter Perkins 2018-7-5
I'm coming to this thread late, so I may be repeating what Walter and Paolo already sorted out. It looks like the root cause was that in R2018a, readtable began supporting directly reading durations as well as datetimes. And because the "time" stamps precede the "date" stamps in the file, this line from the table2timetable doc
"The first datetime or duration variable in T becomes TT's time vector"
explains what happened. Walter's suggestion seems right, although I would have used
dt = T.Date + T.Var4; % csv is missing some col headings
By the way, it's easy to switch a timetable back and forth between absolute and relative time: just add or subtract an offset:
>> tt = timetable([1;2;3],'RowTimes',datetime('now') + minutes(0:2))
tt =
3×1 timetable
Time Var1
____________________ ____
05-Jul-2018 10:33:50 1
05-Jul-2018 10:34:50 2
05-Jul-2018 10:35:50 3
>> t1 = tt.Time(1)
t1 =
datetime
05-Jul-2018 10:33:50
>> tt.Time = tt.Time - t1
tt =
3×1 timetable
Time Var1
________ ____
00:00:00 1
00:01:00 2
00:02:00 3
>> tt.Time = tt.Time + t1
tt =
3×1 timetable
Time Var1
____________________ ____
05-Jul-2018 10:33:50 1
05-Jul-2018 10:34:50 2
05-Jul-2018 10:35:50 3

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