Combine Tables with different record rate
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Hey Everybody,
I need to join two tables by the common Parameter "Time_secs_" which represents the record date of my sensor data. Unfortunately, in one table the record is 0.5 seconds while in the second it is 0.1 seconds. Therefore the second table has 481002 rows while the first only has 80167 rows.
Now I want to join them by their record rate and simply add blank cells for every signal from table 1 to the time_secs_0 0.1, 0.2, 0.25, 0.3, 0.4, 0.6, 0.7, 0.75, 0.8, 0.9 (some signals are also taken every 0.25 seconds, thats why 0.25 and 0.75 are included).
How can I do this? Is there any specification I can make to the "join"-function or will it not work with this at all?
Thanks a lot in advance!
6 个评论
Peter Perkins
2018-8-3
Richard, you can do that (use tables and joins), but if you are using R2016b or later, you will be much happier using timetables and synchronize:
>> tt1 = timetable((1:10)','RowTimes',seconds(0:1:9))
tt1 =
10×1 timetable
Time Var1
_____ ____
0 sec 1
1 sec 2
2 sec 3
3 sec 4
4 sec 5
5 sec 6
6 sec 7
7 sec 8
8 sec 9
9 sec 10
>> tt2 = timetable((11:15)','RowTimes',seconds(0:2:8))
tt2 =
5×1 timetable
Time Var1
_____ ____
0 sec 11
2 sec 12
4 sec 13
6 sec 14
8 sec 15
>> synchronize(tt1,tt2)
ans =
10×2 timetable
Time Var1_tt1 Var1_tt2
_____ ________ ________
0 sec 1 11
1 sec 2 NaN
2 sec 3 12
3 sec 4 NaN
4 sec 5 13
5 sec 6 NaN
6 sec 7 14
7 sec 8 NaN
8 sec 9 15
9 sec 10 NaN
But beware: .1 is not a nice floating point number. You may find that synchronize treats some times that look the same as different, because they are different. At that level of resolution, you are usually better off using the milliseconds function to construct time vectors than using the seconds function.
采纳的回答
Guillaume
2018-7-24
How can I create an additional column within the table which contains all the information of those three others and makes a time out of this?
yourtable.newcolumnname = datetime([zeros(height(yourtable), 3), yourtable.hourcolumn, yourtable.minutecolumn, yourtable.secondcolumn], 'Format', 'HH:mm:ss')
5 个评论
Walter Roberson
2018-10-13
What is the
zeros(height(Minus22_FlightParameter_Hydraulics_Uniform_Table),6),
part there for? That is going to generate 6 columns of zeros, and then you add on 6 more columns of numeric values, for a total of 12 columns.
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