# HOW TO ADD ONE COLUMN BASED ON ANOTHER COLUMN

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Tanmoyee Bhattacharya on 30 Jun 2024
I have a file containing some columns.
hru sub year mon area gw_rchrg
1 1 2016 1 61 1.87
2 1 2016 1 233 2.91
3 1 2016 1 345 5.45
4 1 2016 1 600 1.23
5 1 2016 1 400 2.67
6 1 2016 1 235 1.34
7 2 2016 1 123 3.67
8 2 2016 1 178 4.78
9 2 2016 1 345 1.56
10 2 2016 1 430 2.67
11 2 2016 1 250 1.12
12 2 2016 1 278 2.12
I have a excel file which has 7 colums. In colum 2 there are rows containing 1 and 2. I want to do some operations.
The second column as 1 value. I want to multiply the values of column 5 and column 6 and add them according to 1 value if column 2. Similarly do it for 2 values of column 2. If there is any code for this?

Matlab Pro on 30 Jun 2024
You need to write more clearer with less errors;
You wrote
• "I have a excel file which has 7 colums" - it has only 6 columns
• "The second column as 1 value" - not clear
• "I want to multiply the values of column 5 and column 6 and add them" Multiply - OK, "and then add them - what exactly to add to the multiplication result?
idx = data.SUB == 1;
mult = data.AREAkm2 .* data.GW_RCHGmm;
mult(~idx) = nan; % Make all values where "SUB ~=1" : NaN
data.('new_column') = mult;
Good luck
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Matlab Pro on 3 Jul 2024
Moved: Voss on 3 Jul 2024
Do you mean you want to create a new column for each unique value in Column #2?
If so- here is a possible solution. I have timed it. it take no time to create 60 new columns based on 60 unique values in colunmn #2:
function tanmoyee_code()
% Creating logical indexes per value of the 'SUB' column (#2)
un_subs = unique(data.SUB);
idxes = arrayfun(@(x) data.SUB==x, un_subs, 'UniformOutput', false);
fld_names = strsplit(sprintf('sub_%d~',un_subs),'~');
fld_names(cellfun(@isempty ,fld_names)) = []; % chop empty entries
mult = data.AREAkm2 .* data.GW_RCHGmm;
tic
for iFld = 1:length(fld_names)
fld1 = fld_names{iFld};
tmp = mult;
tmp(~idxes{iFld}) = nan;
data.(fld1) = tmp;
end
toc
Tanmoyee Bhattacharya on 4 Jul 2024
Edited: Tanmoyee Bhattacharya on 4 Jul 2024
Sir
Thank you for you kind reply.
I think I again fail to make you understand. Sir, This time I give an example
hru sub year mon area gw_rchrg multiplication sum
1 1 2016 1 61 1.87 61*1.87 =114.07 114.07+678.03+1880.25+738+1068+314.9
2 1 2016 1 233 2.91 233*2.91=678.03 = 4793.25 (for 1)
3 1 2016 1 345 5.45 345*5.45=1880.25
4 1 2016 1 600 1.23 600*1.23=738
5 1 2016 1 400 2.67 400*2.67=1068
6 1 2016 1 235 1.34 235*1.34=314.9
7 2 2016 1 123 3.67 123*3.67=451.41 451.41 +850.84+538.20+1148.10+280+589.36
8 2 2016 1 178 4.78 178*4.78=850.84 = 3857.91 (for 2)
9 2 2016 1 345 1.56 345*1.56=538.20
10 2 2016 1 430 2.67 430*2.67=1148.10
11 2 2016 1 250 1.12 250*1.12=280
12 2 2016 1 278 2.12 278*2.12=589.36