I tried
myTable.MyField{:}='AAA'
myTable.MyField(:)='AAA'
myTable.MyField{:}={'AAA'}
myTable.MyField{:}=deal('AAA')
but all failed.
Is there any way?
MATLAB requires:
To assign to or create a variable in a table, the number of rows must match the height of the table.
So it would be:
myTable.MyField = repmat('AAA', length(myTable.MyField), 1);
or if you know the column number of MyField, you can do:
myTable(:,colnum) = {'AAA'}; %where colnum is the column number
or otherwise if you don't know the column number, you can directly use the column name as well:
myTable(:,'MyField') = {'AAA'};
Related
I am a new user of MatlabR2021b and I have a table where the last column (with name loadings) spans multiple sub-columns (all sub-columns were added under the same variable/column and are threated as one column). I wanto to create a For loop that goes through each separate loading column and iterates through them, prior to creating a tbl that I will input into a model. The sub-columns contain numbers with rows corresponding to the number of participants.
Previously, I had a similar analogy where the loop was iterating through the names of different regions of interest, whereas now the loop has to iterate through columns that have numbers in them. First, the numbers in the first sub-column, then in the second, and so on.
I am not sure whether I should split the last column with T1 = splitvars(T1, 'loadings') first or whether I am not indexing into the table correctly or performing the right transformations. I would appreciate any help.
roi.ic = T.loadings;
roinames = roi.ic(:,1);
roinames = [num2str(roinames)];
for iroi = 1:numel(roinames)
f_roiname = roinames{iroi};
tbl = T1;
tbl.(roinames) = T1.loadings(:,roiname);
**tbl.(roinames) = T1.loadings_rsfa(:,roiname)
Unable to use a value of type cell as an index.
Error in tabular/dotParenReference (line 120)
b = b(rowIndices,colIndices)**
Similar to Excel, I need to find out how to filter out rows of a table that do not contain a certain string.
For example, I need only rows that contain the letters "MX". Within the sheet, there are rows with strings like ZMX01, MX002, and US001. I would want the first two rows.
This seems like a simple question, so I am surprised I couldn't find any help for this!
It is similar to the question Filter on words in Matlab tables (as in Excel)
You may not find a lot of information on tables in MATLAB, as they were introduced with version R2013a, which is not that long ago. So, about your question: Let's first create a sample table:
% Create a sample table
col1 = {'ZMX01'; 'MX002'; 'US001'};
col2 = {5;7;3};
T = table(col1, col2);
T =
col1 col2
_______ ____
'ZMX01' [5]
'MX002' [7]
'US001' [3]
Now, MATLAB provides the rowfun function to apply any function to each row in a table. By default, the function you call has to be able to work on all columns of the table.
To only apply rowfun to one column, you can use the 'InputVariables' parameter, which lets you specify either the number of the column (e.g. 2 for the second column) or the name of the column (e.g. 'myColumnName').
Then, you can set 'OutputFormat' to 'uniform' to get an array and not a new table as output.
In your case, you'll want to use strfind on the column 'col1'. The return value of strfind is either an empty array (if 'MX' wasn't found), or an array of all indices where 'MX' was found.
% Apply rowfun
idx = rowfun(#(x)strfind(x,'MX'), T, 'InputVariables', 'col1', 'OutputFormat', 'uniform');
The output of this will be
idx =
[2]
[1]
[]
i.e. a 3-by-1 cell array, which is empty for 'US001' and contains a positive value for both other inputs. To create a subset of the table with this data, we can do the following:
% Create logical array, which is true for all rows to keep.
idx = ~cellfun(#isempty, idx);
% Save these rows and all columns of the table into a new table
R = T(idx,:);
And finally, we have our resulting table R:
R =
col1 col2
_______ ____
'ZMX01' [5]
'MX002' [7]
I have two columns of dates and I want to run a query that returns TRUE if there is a date in existence in the first column and in existence in the second column.
I know how to do it when I'm looking for a match (if the data entry in column A is the SAME as the entry in column B), but I don't know know how to find if data entry in column A and B are in existence.
Does anyone know how to do this? Thanks!
If data in a column is present, it IS NOT NULL. You can query for that on both columns, with and AND clause to get your result:
SELECT (date1 IS NOT NULL AND date2 IS NOT NULL) AS both_dates
FROM mytable;
So, rephrasing:
For any two entries in table x with date columns a and b, is there some pair of rows x1 and x2 where x1.a = x2.b?
If that's what you're trying to do, you want a self-join, e.g, presuming the presence of a single key column named id:
SELECT x1.id, x2.id, x1.a AS x1_a_x2_b
FROM mytable x1
INNER JOIN mytable x2 ON (x1.a = x2.b);
I executed a stored procedure in java which results into a table of 16 column and 3600 rows.Now I want to access 3 column of the retrieved table in row by row fashion and calculate the average of all column in row wise fashion.To do this,I need to access values of columns one by one .How to do it. My code for accessing column is
while (rs.next())
{
a1=rs.getDouble(7);
a2=rs.getDouble(8);
a3=rs.getDouble(10);
sum +=(a1+a2+a3);
}
return sum/3;
but through this,i think i'am getting a total average of all the columns .But i need average of column row by row i.e average of all three column of first row,then second row ...like this.
You are indeed adding all the values from 3 columns and doing row by row addition.
If you want row by row, then for each entry that you get from database you need to store the result in a list like below and return it where needed:
List<Double> averageList = new ArrayList<Double>();
while (rs.next())
{
a1=rs.getDouble(7);
a2=rs.getDouble(8);
a3=rs.getDouble(10);
averageList.add((a1+a2+a3)/3.0);
}
return averageList;
If I generate an identity for a table on the column cust-id, I want the next column userid to be cust-id+CID.
E.g. 000000001CID, 0000000002CID
What sql do I include for this?
Similarly if I have 00001 in the column Cust-id and abcd in the column section, the 3rd column must have value 00001abcd
Please let me know the solutions
You just need to create a trigger. Something like
CREATE TRIGGER A
BEFORE INSERT ON TABLE B
REFERENCING NEW AS N
FOR EACH ROW
BEGIN
SET N.userid = N.CUST_ID + N.CID ;
IF (N.CUST_ID = '00001' AND N.SECTION = 'abcd') THEN
SET N.THIRD = N.CUST_ID + N.SECTION
END IF;
END #
By the way, generating values in column shows that your module is not normalize, and sometimes this is a source of errors.