# Zero mean là gì, forum machine learning cơ bản

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I"m trying khổng lồ reproduce an algorithm designed in a paper. And everything is going well except one thing:

It says we considered the lengths zero-meaned accelerometer vectors & created a feature for the mean and standard deviation of this value. and I vì not underst& what is it zero-meaned vectors?

Example dataset:

Can any toàn thân help me?

I found only this information https://www.quora.com/What-does-it-mean-when-a-vector-is-zero-mean but I"m not sure about it.

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Thank you.

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asked Sep 25 "16 at 13:59 ArsenArsen
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"Zero-meaned" means the vector has been transformed so that its mean is 0.

Typically, you would vày this by subtracting the mean of each column from that column. (This is for dimensional as well as algorithmic reasons; you don"t want to subtract a person"s weight from their height.)

It sounds lượt thích here they"re actually talking about the row mean--that is, \$(-0.6946377, 12.680544, 0.50395286)\$ would be transformed khổng lồ \$(-4.857924, 8.5172577, -3.65933344, 4.1632863, 7.40047)\$, where the first three are the original features minus the row mean, the fourth is the row mean, & the fifth is the standard deviation of the original features.

This would make sense if the three have sầu the same units (if they"re all accelerations at the same scale, this works), and so you want a separate measure of how much it"s being accelerated at all & how much it"s being accelerated in a particular direction.

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edited Sep 25 "16 at 16:12
answered Sep 25 "16 at 16:10 Matthew GravesMatthew Graves
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