Assign a certain element value if two array elements are equal

Hello. I have two arrays called data1 and data1arranged:

data1 =

    100.5000
    107.4000
    .
    .
    107.4000
    105.6000

data1 is 95x1 double and data1arranged is a 263x1 double. I want to compare every value of data1 to data1arranged and assign what element rank/number it is. Here's my code:

for i=1:numel(data1)
for j = 1:numel(data1arranged)
        if ((data1(i,1))==(data1arranged(j,1)))
            obsseq(i,1) = observation(j,1);
        end   
    end
end

my data1arranged is just basically an array of numbers from min(data1) to max(data1) with an increment of 0.1. That is, if my min(data1) is 94.2 and if my max(data1) is 120.4, then my data1arranged will just be

data1arranged =

94.2
94.3
94.4
.
.
.
120.3
120.4

observation array is just basically a numbering sequence of data1arranged. That is, from lowest to highest, I would just number it from 1 up to 263. That is basically the equivalent rank of every element in data1arranged.

Observation array is:
for i = 1:numel(data1arranged)
observation(i,1) = i
end

But then every time, I will run the above mentioned for loop, my obsseq will give me the logical value of

        (data1(i,1))==(data1arranged(j,1))

of which I'm not interested in. I want that, if the logical value is true, then the obsseq array will fill up with the corresponding value from the observation array elements. Can anyone please help me? Thank you so much!

Answer 1

[dpb]

doc ismember

NB: Be aware ismember is exact equality and floating point rounding can wreak havoc on comparisons if values between the two arrays aren't computed similarly. Later versions have ismembertol to handle this.