Replacing a numberless string in matrix with a number

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deejt
deejt 2021-1-27
评论： Stephen23 2021-1-27
Hello,
I have a matrix that contains a column with participants' gender written as strings ("female" vs" "male").
I would like to change females to 1 and males to 0. How would I do that?
Thank you!

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回答（2 个）

Stephen23
Stephen23 2021-1-27
Ran in:
Where V is that column:
V = ["female";"male";"female";"male";"male";"female"]
V = 6×1 string array
"female" "male" "female" "male" "male" "female"
X = strcmpi(V,"female")
X = 6x1 logical array
1 0 1 0 0 1
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deejt
deejt 2021-1-27
Ok, thank you! it seemed to have been the comma.
But now it seems lucky, that I only had two different strings in my current code.
Out of interest for the future:
What would I do if I had for example a column dedicated to colour = 'green', 'blue', 'yellow' and 'purple' and I want to change these strings as following:
'green' = 1
'blue' = 2
'yellow' = 3
'purple' = 4
Where and how would I then specify the values I want to use to replace the strings?
Stephen23
Stephen23 2021-1-27
编辑：Stephen23 2021-1-27
For the values 1..N I would simply use the second output of ismember.
If you want to specify totally arbitrary values, then probably the easiest way would be to define a vector of those arbitrary values and then use indexing (e.g. the second output of ismember) to select from that vector.
You will find num2cell useful for both of these.

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Steven Lord
Steven Lord 2021-1-27
Ran in:
I would likely use a string array.
colors = ["green"; "blue"; "yellow"; "purple"];
% Make some sample data
ind = randi(numel(colors), 10, 1);
arrayOfColors = colors(ind);
whichColor = NaN(size(arrayOfColors));
for c = 1:numel(colors)
whichColor(arrayOfColors == colors(c)) = c;
end
% Display results side by side
results = table(ind, arrayOfColors, whichColor)
results = 10x3 table
ind arrayOfColors whichColor ___ _____________ __________ 4 "purple" 4 3 "yellow" 3 1 "green" 1 2 "blue" 2 2 "blue" 2 1 "green" 1 1 "green" 1 3 "yellow" 3 4 "purple" 4 4 "purple" 4
This also works if arrayOfColors was a categorical array, though for a categorical array there's an easier way to report which element of the valueset was used to generate each element of the categorical array by just using the double function.
colorCats = categorical(arrayOfColors, colors);
results.colorCats = colorCats;
results.whichCat = double(colorCats)
results = 10x5 table
ind arrayOfColors whichColor colorCats whichCat ___ _____________ __________ _________ ________ 4 "purple" 4 purple 4 3 "yellow" 3 yellow 3 1 "green" 1 green 1 2 "blue" 2 blue 2 2 "blue" 2 blue 2 1 "green" 1 green 1 1 "green" 1 green 1 3 "yellow" 3 yellow 3 4 "purple" 4 purple 4 4 "purple" 4 purple 4
all(whichColor == ind)
ans = logical
1
all(results.whichCat == ind)
ans = logical
1

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