combining 4 csv files with and without headers

I have 4 .csv files that is generated from an equipment that I am using. One of the csv files has 4 columns with a heading, and the other 3 csv files have between 2-3 columns without heading. I would like to use a column from each csv file as a reference as to where the values should be placed. The file with 4 colums is the "master" file with a timestamp for the duration of the experment and the other three csv files have unique timestamps that corrrespond to somewhere in the "master" file.

Is this something that is possilbe to do in Matlab?

[Adam Danz]

It sounds like you're working with timetables but it's unclear how you'd like the tables to be combined. Providing a short example may help.

[Terry Yin]

Hi Adam,

Would it be possible to email you the files that are in question so it can be easier for you to look at and understand?

Thanks

[Adam Danz]

No, but you could attach files to a comment or, better yet, provide a quick sample of just a few rows from each of the 3 csv files and a description of how the data should be merged. Once the problem is clearly defined my bet is that the solution will be staightforward.

[Terry Yin]

This is from the FP file

FrameCounter Timestamp Flags Region0

0 13084.4048 7 0.02967622

1 13084.4429 7 0.02961321

2 13084.481 7 0.02967732

The Timestamp that is marked originates from the time when the machine was turned on. While other files generated from the file is based of milliseconds of the day. So there is another file that looks at the frame (column 1) and pairs it with the time of the day, and this file has no heading.

0 48786598

1 48786634.2

2 48786672.8

3 48786710.3

There is also another file generated based on a keydown that I hit. The timestamp is based off the "time of day", which is why we have to convert the "frame counter" to a new timestamp. This will only show something if I press the space bar, and this file has no header either.

Space 49154818.5

Space 49210956.1

Space 49218482.5

Space 49253519.6

Basically what I want to do is combine the first two files together so I have a reference point where I can designate where the keydown was pushed to idenitfy some response.

Hope this helps clarify my issue (there is another file that is generated without a heading, but is not important to the experiment that I am conducting)

Answer 1

[Adam Danz]

You can use outerjoin to join the first 2 tables into 1 table. It's not entirely clear how you're indexing the 3rd table into the first two but it sounds like you want the closest time stamps in table 3 to the time stamps in table 2. These two steps are demonstracted below using the demo data you provided.

% Create 3 tables
d1 = [ 0  13084.4048  7  0.02967622 
  1  13084.4429  7  0.02961321 
  2  13084.481  7  0.02967732 ]; 
T1 = array2table(d1, 'VariableNames', {'FC','timestamp','Flags','Region'})

T1 = 3×4 table
    FC    timestamp    Flags     Region 
    __    _________    _____    ________

    0       13084        7      0.029676
    1       13084        7      0.029613
    2       13084        7      0.029677

d2 = [  0  48786598 
  1  48786634.2 
  2  48786672.8 
  3  48786710.3 ]; 
T2 = array2table(d2, 'VariableNames', {'FC','time_ms'})

T2 = 4×2 table
    FC     time_ms  
    __    __________

    0     4.8787e+07
    1     4.8787e+07
    2     4.8787e+07
    3     4.8787e+07

d3 = {  'Space'  49154818.5 
  'Space'  49210956.1 
  'Space'  49218482.5 
  'Space'  49253519.6};
T3 = cell2table(d3, 'variablenames', {'Key','time_ms'})

T3 = 4×2 table
       Key        time_ms  
    _________    __________

    {'Space'}    4.9155e+07
    {'Space'}    4.9211e+07
    {'Space'}    4.9218e+07
    {'Space'}    4.9254e+07

% Join tables 1 and 2
T12 = outerjoin(T1, T2, 'keys','FC','MergeKeys',true)

T12 = 4×5 table
    FC    timestamp    Flags     Region      time_ms  
    __    _________    _____    ________    __________

    0       13084         7     0.029676    4.8787e+07
    1       13084         7     0.029613    4.8787e+07
    2       13084         7     0.029677    4.8787e+07
    3         NaN       NaN          NaN    4.8787e+07

% Find the row of the closest time stamples in T12 to the time stamps in T3
[~, minidx] = min(abs(T12.time_ms - T3.time_ms'))

minidx = 1×4

4 4 4 4

T12(minidx,:)

ans = 4×5 table
    FC    timestamp    Flags    Region     time_ms  
    __    _________    _____    ______    __________

    3        NaN        NaN      NaN      4.8787e+07
    3        NaN        NaN      NaN      4.8787e+07
    3        NaN        NaN      NaN      4.8787e+07
    3        NaN        NaN      NaN      4.8787e+07

[Terry Yin]

Thanks for your help. Greatly appreciated