# How to separate rows from an array

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Alex am 27 Okt. 2011
Hey guys,
I am fairly new to MatLab and I am trying to figure out how to seperate out certain rows from my main array into a new array based on the contents of my first column.
For Example
column 1 column 2 column 3
1 Cash 5.00
2 Credit 10.00
3 Debt 1.50
So lets say I wanted to separate out cash and credit and add them to a new array so I can ultimately sum the contents of column 3 together.
Something along the lines of "if column 1 is => 0 & =<2, move whole rows to " array 2"
Thanks for your help.
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Fangjun Jiang am 27 Okt. 2011
You can use {}Code format next time.

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### Antworten (3)

Fangjun Jiang am 27 Okt. 2011
If you matrix is numerical, it is actually easy.
a=[1 5.00
2 10.00
3 1.50
1 5.00
2 10.00
3 1.50];
index=a(:,1)>0 & a(:,1)<3;
b=a(index,:)
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Fangjun Jiang am 27 Okt. 2011
What are you talking about? Run the xlsread() and your data will be put in the 'a' variable. The code above is just an example showing how it works on a cell array.
Alex am 28 Okt. 2011
Sorry, I just confused myself. This works perfectly. Thank you so much for your help.

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Honglei Chen am 27 Okt. 2011
Here is a simple example:
>> x = rand(3,3)
x =
0.9055 0.6581 0.2495
0.2045 0.1836 0.3782
0.9654 0.3151 0.5356
>> y = x(x(:,1)>0.5,2)
y =
0.6581
0.3151
HTH
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Alex am 28 Okt. 2011
Here's an example using the text 'credit' and 'cash' to find and sort out what you want easily.
col_2 = {'credit' 'credit' 'cash' 'cash'};
col_3 = [ 1 2 3 4 ];
%find the credit rows
credit_rows = strcmp(col_2,'credit');
%find indexes of credit row
credit_index = find(credit_rows == 1);
%now we have the index of each credit value, so we can sum these, or move them
only_credit_col = col_3(credit_index);
total_credit = sum(only_credit_col);
%remove the credit cells from the original column - this will leave you a column with only cash values
col_3(credit_index) = [];
cash_col = col_3;
cash_tot = sum(cash_col);
results: credit_col = [1 2] total_credit = 3
cash_col = [3 4] total_cash = 7 total_cash = 7
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Fangjun Jiang am 28 Okt. 2011
credit_rows is a logic array. It can be used for index. You don't need to generate the credit_index using find()
col_2 = {'credit' 'credit' 'cash' 'cash'};
col_3 = [ 1 2 3 4];
%find the credit rows
credit_rows = strcmp(col_2,'credit');
%now we have the index of each credit value, so we can sum these, or move them
only_credit_col = col_3(credit_rows);
total_credit = sum(only_credit_col);
%remove the credit cells from the original column - this will leave you a column with only cash values
col_3(credit_rows) = [];
cash_col = col_3;
cash_tot = sum(cash_col);

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