calculate data based on previous values and replace it at negative and zeros values

there is different data in the column in excel (REACTIVE_Y_PH), which has some negative and zeros values also, these values should be replaced by calculating the average of previous data and replace them.

[Image Analyst]

Not the average of the data on each side of the bad data? Just on the previous side? OK, but average how many on the previous side only? This is easy to do with conv() and logical indexing, so just try it. Even easier if you have the Image Processing Toolbox. Let me know if you can't figure it out.

[KSSV]

Your data has negative values in the first index also i.e 1:17 values are negative..with what you want to replace them?

[MUKESH KUMAR]

can take last 5 or 10 values for average and replace it at zeros or we can directly change -ve values to +ve by sign.

[Image Analyst]

What were the "last" 5 values when the first few are to be replaced? There are no elements at indexes -4 to 0. Or did you mean the "last" ones at the other end of the array, like from vec(end-4:end)?

[MUKESH KUMAR]

No, previous values of the column before that value, Like in the image, first 15 values in the second column are negative so make them positive and at 16th row '0' that will be replaced by previous 5 values average((11.5+9.2+9.2+6.9+4.6)/5).Similarly do for next values

Answer 1

[KSSV]

[num,txt,raw] = xlsread('sample.xls') ;
data = cell2mat(cellfun(@str2num,txt(:,2),'un',0)) ;

%%fill negative and zeros 
idx = data<=0 ;
data(idx) = NaN ;
data = fillmissing(data,'previous') ;

[MUKESH KUMAR]

please consider my last comment also,thanks for your support