I get the following error message: "'Value' must be a double scalar." in appdesigner

Question

Shanice Steinecke 2023-7-19

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1997733-i-get-the-following-error-message-value-must-be-a-double-scalar-in-appdesigner

编辑： Stephen23 2023-7-19

In my appdesigner code I want to get some values from my excel sheet (these values depend on the choice of the list box item):

if value == '2'

F = readtable("CO2_neu.xlsx","Sheet","List","Range","E4");

app.weight_1.Value = double(F.(1));

...

elseif value == '7'

G = readtable("CO2_neu.xlsx","Sheet","List","Range","E9");

app.weight_1.Value = double(G.(1));

end

For the value in cell E9 everything works and the respective value is displayed in my app. For all the other values from E4 - E8 I get the error message: 'Value' must be a double scalar even though these are also just numbers that I entered into the excel sheet and I use the exact same code to get them. Here you can see the excel sheet.

As the code works for the value in E9, I don't understand what the error is for the other cells?

I would be really grateful if someone could help me to fix this error!

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Stephen23 2023-7-19

编辑：Stephen23 2023-7-19

在 MATLAB Online 中打开

Rather than using EQ to compare text like this:

if value == '2'

I strongly recommend that you use STRCMP or something similar. Or even SWITCH. Note that you could anyway replace that entire IF/ELSEIF... by defining the Range in terms of that value. Perhaps something like this:

N = 2;
R = "E"+(N+2);
T = readtable("CO2_neu.xlsx","Sheet","List","Range",R)

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

VBBV 2023-7-19

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1997733-i-get-the-following-error-message-value-must-be-a-double-scalar-in-appdesigner#answer_1275398

编辑：VBBV 2023-7-19

Try using readmatrix function instead of readtable

3 个评论
显示 1更早的评论隐藏 1更早的评论

Shanice Steinecke 2023-7-19

编辑：Shanice Steinecke 2023-7-19

When using readmatrix I get the same error

VBBV 2023-7-19

编辑：VBBV 2023-7-19

Ok. Perhaps you are using a small case value instead of Value for other cells. Can you check once ? Also check if the remaining cells have any characters or ASCII symbols inside them

请先登录，再进行评论。