Changing data from long form to short form

Hi all,

I wondered if someone might be able to help - with what might seem like a super easy tast.

I have data in longform i.e. (a simple example of what I have below, example 1), but I ideally need it in short form i.e. one row per participant see example 2.

Example 1.

Participant_ID Trial RT

1 1 342

1 2 346

1 3 534

2 1 242

2 2 131

2 3 531

Example 2.

Participant_ID 1_RT 2_RT 3_RT

1 342 346 534

2 242 131 531

Is there a simple way I can do this?

Thank you in advance,

Rachel

Answer 1

[Steven Lord]

Participant_ID = [1; 1; 1; 2; 2; 2];
Trial = [1; 2; 3; 1; 2; 3];
RT = [342; 346; 534; 242; 131; 531];

t = table(Participant_ID, Trial, RT);
unstackedTable = unstack(t,'RT','Trial');

Answer 2

[Rik]

You can use the participant ID and trial ID as the indices and either use accumarray or sub2ind to fill the matrix with the values. I would suggest sub2ind if you can guarantee that every combination of trial and participant is unique.

Answer 3

[Walter Roberson]

Under the assumption that all of the information for each participant is gathered together and that there are exactly the same number of data points per participant, then:

[Particpant_ID(1:number_of_trials:end), reshape(RT, number_of_trials).']