How to do when the inputs ranges for neural network are not so uniform in magnitude ?

Hi,i'm trying to create neural network for classification of EEG signal in which i extacted 9 features that i will use it as inputs for neural network but the problem is that my inputs ranges are not so uniform in magnitude i mean some input can take a very high value numerically compared to other inputs so the big numbers will mask the effect of the smaller numbers. I used the preprocessing function 'mapminmax' but i still have a bad performance so when i do some research i found that i should Transform each input that has always a positive value into logarithm values. Matlab will take these transformed values and apply the normalization to them [-1,1]. For prediction, i should enter not the actual values but the logarithm of the input to the ANN. So i want tp know is this right ? and can i do this transformation of my innputs with matlab?

This how my original input looks like

Answer 1

[Greg Heath]

Typically, MAPMINMAX only fails when outliers are present.

Try MAPSTD to identify and modify (or delete?) outliers

Hope this helps.

Thank you for formally accepting my answer

Greg

[afef]

Did you mean MAPSTD??? because when i search for MAPST it i coldn't find it

[Greg Heath]

Yes.

[afef]

i tried to use MAPSTD without logarithme transformation and with logarithme transformation and i found that the accuracy improve just little bit with logarithme transformation but not still very good . Is it logical?

[Greg Heath]

When you used mapstd on the log values what were the 9 minimum and maximum ranges?

[afef]

i don't understand your question ver well but i think that the ranges of all the values will be [-1,1] isn't?

[Greg Heath]

No.

MAPSTD yields zero mean and unit variance. Mins and Maxes will be different. I use this for outlier detection.

MAPMINMAX yields [ -1 1 ] mins and maxes. Means and Variances will be different.

Hope this helps.

Greg

[afef]

this is an example of log transformed data

and this is after application of MAPSTD

i want to know is it correct to use it for my case ?

[Greg Heath]

I can't tell with tabulations. I tend to relay on linear and scatter plots.

Greg

[afef]

How can i do this linear and scatter plots ?