How do I change my code to stop a for loop simply replacing rows of outputs in a uitable?

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function drainage_system_design_rough
n=input('How many pipes are in the system? ');
PRef=[1:1:n];
for PRef=1:n
disp('Pipe reference:')
disp(PRef)
L=input('Pipe Length:');
schedule=input('Do you want to add pipe to drainage schedule? (Yes=1, No=0)?: ');
if schedule==1
col={'Pipe Length(m)'};
row={PRef};
dat={L};
uitable('columnname',col,'rowname',row,'data',dat);
end
end
I am really new to MATLAB but want to create a simple table to store drainage system information. I want the rows of the table to be labelled by the pipe references (the number of which depend on the number of pipes in the system). However, each time the for loop is executed only the information for the last pipe is stored in the table and it replaces the informaton for the previous pipe. If any could help me code this better so I had a table that added rows each time the for loop was executed but also stored the previous rows, that would be much appreciated.

Accepted Answer

Cris LaPierre
Cris LaPierre on 4 Jun 2021
Uitables do not have an append mode. When you specify data, you either need to specify the specific row, or reload all the data. Given the functionality you want, my approach would be to first extract the existing values/rownames, then append the new values to the end, and pass the combined values back in as the table data.
fig = uifigure;
uit = uitable(fig,'columnname','Pipe Length(m)',"RowName",{},"Data",[]);
n=input('How many pipes are in the system? ');
PRef=[1:1:n];
for PRef=1:n
disp('Pipe reference:')
disp(PRef)
L=input('Pipe Length:');
schedule=input('Do you want to add pipe to drainage schedule? (Yes=1, No=0)?: ');
if schedule==1
uit.Data = [uit.Data;L];
uit.RowName = {uit.RowName{:};PRef};
end
end
  7 Comments
Ed Paddock
Ed Paddock on 7 Jun 2021
Hi Cris, thanks for that. Can you please see the below code. I have expandad the original code to now include multiple inputs that I require in my uitable so I need to keep the structure of the for loop to input the different values for the different pipes. As mentioned before, how can I changed this code to get rid of the error message and expand it for multiple inputs that need to be separate colums?
function drainage_system_design_rough3
fig = uifigure;
uit = uitable(fig,'columnname','Pipe Length(m)',"RowName",{},"Data",[]);
n=input('How many pipes are in the system? ');
PRef=[1:n];
for PRef=1:n
disp('Please input data for the following pipe:')
disp('Pipe reference')
disp(PRef)
USMHRef=input('Upstream Manhole Reference: ');
Dia=input('Pipe diameter (mm): ');
L=input('Pipe length (m): ');
K=input('Pipe roughness value: ');
USCL=input('Upstream cover level (mAOD): ');
USIL=input('Upstream invert level (mAOD): ');
G=input('Desired pipe gradient: ');
schedule=input('Do you want to add pipe to drainage schedule? (Yes=1, No=0)?: ');
if schedule==1
uit.Data = [uit.Data;L];
uit.RowName = {uit.RowName{:};1:n};
end
end

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More Answers (1)

Benjamin Kraus
Benjamin Kraus on 4 Jun 2021
The code as it is currently written is creating a brand-new uitable every time the loop runs.
You need to update the code to either:
  1. Collect all the data, then create a uitable once with all the data.
  2. Create a uitable once at the beginning, then add data to the existing uitable.
Example of option 1:
ncols = 4;
nrows = 4;
colnames = cell(ncols,1);
rownames = cell(nrows,1);
data = cell(nrows,ncols);
for r = 1:nrows
for c = 1:ncols
rownames{r} = ['Row ' num2str(r)];
colnames{c} = ['Column ' num2str(c)];
data{r,c} = r*c;
end
end
uitable('ColumnName', colnames, 'RowName', rownames, 'Data', data)
Example of option 2:
tbl = uitable;
tbl.RowName = {};
tbl.ColumnName = {};
tbl.Data = {};
ncols = 4;
nrows = 4;
for r = 1:nrows
for c = 1:ncols
tbl.RowName{r} = ['Row ' num2str(r)];
tbl.ColumnName{c} = ['Column ' num2str(c)];
tbl.Data{r,c} = r*c;
end
end
The end result of both will be the same, but the first option is significantly more efficient.
  1 Comment
Ed Paddock
Ed Paddock on 7 Jun 2021
Hi Benjamin, thank you for the help. I have tried to implement both your suggestions into my code.
  • For the first option I find that I get a similar issue to my original problem where only the information for the last pipe I enter through the for loop is stored in the uitable?
  • For the second option I find that no data is added to the table that is created at the start of the code so I am just left with a blank table?
Below I have pasted the two codes I have used (note that the inputs have been expanded compared to my original) and any help you could provide would be appreciated:
Table created at end of code:
function drainage_system_design_rough2
n=input('How many pipes are in the system? ');
PRef=[1:n];
for PRef=1:n
disp('Please input data for the following pipe:')
disp('Pipe reference')
disp(PRef)
USMHRef=input('Upstream Manhole Reference: ');
Dia=input('Pipe diameter (mm): ');
L=input('Pipe length (m): ');
K=input('Pipe roughness value: ');
USCL=input('Upstream cover level (mAOD): ');
USIL=input('Upstream invert level (mAOD): ');
G=input('Desired pipe gradient: ');
end
ncols = 7;
nrows = n;
for r = 1:nrows
for c = 1:ncols
rownames = {1:n};
colnames = {'Pipe Dia(mm)','Pipe Gradient','Pipe Length(m)','Pipe Roughness','US MH','US CL(mAOD)','US IL(mAOD)'};
data = {Dia,G,L,K,USMHRef,USCL,USIL};
end
end
uitable('ColumnName',colnames,'RowName',rownames,"Data",data);
Table created at start of code:
function drainage_system_design_rough3
tbl=uitable;
rownames={};
colnames={};
data={};
n=input('How many pipes are in the system? ');
PRef=[1:n];
for PRef=1:n
disp('Please input data for the following pipe:')
disp('Pipe reference')
disp(PRef)
USMHRef=input('Upstream Manhole Reference: ');
Dia=input('Pipe diameter (mm): ');
L=input('Pipe length (m): ');
K=input('Pipe roughness value: ');
USCL=input('Upstream cover level (mAOD): ');
USIL=input('Upstream invert level (mAOD): ');
G=input('Desired pipe gradient: ');
end
ncols = 7;
nrows = n;
for r = 1:nrows
for c = 1:ncols
rownames = {1:n};
colnames = {'Pipe Dia(mm)','Pipe Gradient','Pipe Length(m)','Pipe Roughness','US MH','US CL(mAOD)','US IL(mAOD)'};
data = {Dia,G,L,K,USMHRef,USCL,USIL};
end
end

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