matlab dummyvar is creating extra binary variable

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MB
MB 2019-3-15
编辑： MB 2019-3-16
Let's say I have a categorical variable with level {'1', '2', '3'}. Now in ideal case, there should be 2 binary variable - b0 and b1 and above categorical variable should be mapped as b0=0,b1=0 for '1', b0=1,b1=0 for '2' and b0=0,b1=1 for '3'.
However, Matlab dummyvar is creating b0,b1,b2 binary variables. How can I get only 2 binary variables and above representation?
cat ={'1','2','3'}'
cat1 = categorical(cat)
result = dummyvar(cat1)
result =
1 0 0
0 1 0
0 0 1

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Jeff Miller
Jeff Miller 2019-3-16
I guess there is a typo in your question and you really want ''b0=1,b1=0 for '2'".
Notice that you get what (I think) you want if you just drop the first column created by dummyvar.
This explanation of dummy indicator variables may be helpful: look here
  1 个评论
MB
MB 2019-3-16
Yes- thank you. I have corrected the typo and it seems to be matching with my requirement after dropping the first column.
I was just expecting 'dummyvar' to be equivalent to 'asfactor' in R but apparently it's not.

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