Replace values with a string

Hi,

I am starting to work with Matlab. At the moment I am in the process to write a script, which should highlight outliers.

Therefore I did some calculation and currently I replaced all the outliers with a 1, and normal values with a 0. These are saved in a table (double - intense_RL). These "1s" should be replaced by the element name, which are saved in a string (element_RL). And I cant find a solution therefore.

for m=1:anzahl_elemente
    intens_RL(intens_RL>SP_limit)=1; %ersetzt Ausreisser durch 1
    intens_RL(intens_RL~=1)=0;       %ersetzt nicht Ausreisser durch 0
end

intens_RL( ~any(intens_RL,2), : ) = [];  %löscht Zeilen die nur 0 drin sind
intens_RL( :, ~any(intens_RL,1) ) = [];  %löscht Spalten die nur 0 drin sind

for k=1:anzahl_elemente
    intens_RL(intens_RL==1)=element_RL
end

I receive following error code:

Unable to perform assignment because the left and right sides have a different number of elements.

Error in Versuch4_SPei (line 68)
    intens_RL(intens_RL==1)=element_RL 

The numbers of columns are the same in intens_RL and element_RL (photos). So in the end, if there are for example 5x one in the column of Magnesium, they should be all replaced by [24Mg]+.

I appreciate all help, because I really stuck at this point. :-)

THANK YOU

[Jan]

What is the purpose of this loop:

for m=1:anzahl_elemente
    intens_RL(intens_RL>SP_limit)=1; %ersetzt Ausreisser durch 1
    intens_RL(intens_RL~=1)=0;       %ersetzt nicht Ausreisser durch 0
end

The body does not depend on the loop counter m, so you perform anzahl_elemente times the same assignement.

The same here:

for k=1:anzahl_elemente
    intens_RL(intens_RL==1)=element_RL
end

"which are saved in a string (element_RL)" - according to the code, element_RL is not a string.

"Unable to perform assignment because the left and right sides have a different number of elements." - This means, that the right and left side of an assignment have a different number of elements. Then an assignment is not possible. Example:

A(1:3) = 1:2  % Must fail!

After all, I do not understand, what you are asking for: "These "1s" should be replaced by the element name, which are saved in a string (element_RL)".

[Benjamin Thompson]

Can you post the whole set of code? What is element_RL defined as?

[Stephen23]

Your description "These "1s" should be replaced by the element name, which are saved in a string (element_RL)" and uploaded screenshots indicate that you are trying to assign string elements to a numeric array. That will not work: numeric arrays can only hold numeric data.

[Tatjana Mü]

I attached the matlab script (Versuch4SPei), the csv file with the data, and the two functions I used to read in the data. I am sorry that I didnt offered enough information.

[Tatjana Mü]

@Stephen would it work if I convert the numeric array into a string array? I dont have to calculate anymore, just replacing this.

[Stephen23]

"would it work if I convert the numeric array into a string array?"

Probably (only you can decide this). Of course after that you will no longer have numeric data, but if this is just for displaying or something similar then this might be completely appropriate.

[Tatjana Mü]

@Stephen I tried to convert the numeric array into a string array and replace the 1 with the element namen. But I still get a error message.

str=string(intens_RL)
fas=string(element_RL)

for k=1:anzahl_elemente
    str(str==1)=element_RL
end

I checked the variables and both are signed as "strings"

Error message:

Error using  == 
Comparison between string and double is not supported.

Error in Versuch4_SPei (line 76)
    str(str==1)=element_RL
 

[Voss]

1 is still a number. You would want to compare to "1", i.e.:

str(str=="1")=element_RL

(This will get past that particular error, but it's still not gonna do what you want.)

[Stephen23]

@Tatjana Mü: or, rather than using indexing, you could then use STRREP or similar.

[Voss]

Also, regarding the logic here:

intens_RL(intens_RL>SP_limit)=1; %ersetzt Ausreisser durch 1
intens_RL(intens_RL~=1)=0;       %ersetzt nicht Ausreisser durch 0

In the first line you are saying, "if any element is an outlier, then set it to 1", and in the second line you are saying, "if any element is not 1, then set it to 0" which is not the same as what you mean to say: "if any element is not an outlier, then set it to 0". To see the difference, consider the situation where, right before those lines are executed, an element of intens_RL is equal to 1 and it's not an outlier. The first line will correctly leave it alone, but then the second line there will also leave it alone when it should be set to 0.

Maybe this situation would never arise in your data, but in general it is not what you want. It can more properly (and clearly) be written as:

is_outlier = intens_RL > SP_limit;
intens_RL(is_outlier) = 1;  % ersetzt Ausreisser durch 1
intens_RL(~is_outlier) = 0; % ersetzt nicht Ausreisser durch 0

Answer 1

[Shivam]

Hello Tatjana,

Based on the details you've shared, it appears that you are encountering an error when trying to assign element names to an intensity array that contains values of 1.

After reviewing and debugging the provided code and converting the intens_RL array to a string type, you can see that 'intens_RL' is a 3x4 string array and 'element_RL' is a 1x5 string array, as shown below:

>> intens_RL

    "0"    "0"    "1"    "1"
    "0"    "1"    "0"    "0"
    "1"    "0"    "0"    "0"

>> element_RL

    "[23Na]+"    "[24Mg]+"    "[189Os]+"    "[209Bi]+"    "UO+"

And to perform the following assignment operation, i.e.

    intens_RL(intens_RL == "1") = element_RL

the number of elements in the 'intens_RL' matrix with the value "1" must match the number of elements in the 'element_RL' array. However, 'intens_RL' contains four "1"s, and 'element_RL' consists of five strings.

You can reconsider the calculations performed to calculate the 'intens_RL' array to deal with the size mismatching.

I hope it helps in resolving the error.

Thanks