In a table, when I try assigning a value to a new column based on some criteria, I get error that "assignment to elements using simple assignment statement is not supported"

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Jorge
Jorge 2024-9-16
评论： Jorge 2024-9-17
I have a table for which I create an index where the values in a particular column are not NaN. I then try to use this index to create an entry into a new array and replace the values at the corresponding index (preloaded with '0000') with '0001'. I will then add this array to the table as a new column.
My intention is to fill the corresponding indx in the column with '0001', if the value in the newTable.PEM1_GA_Current_Estimate_Error a valid number (not NaN).
PEM1b ='0001';
PEM2b ='0010';
PEM3b = '0100';
PEM4 = '1000';
temp={};
indx=(find(newTable.PEM1_GA_Current_Estimate_Error ~= NaN))
temp ={repmat('0000',size(newTable,1),1)}
temp{indx} = PEM1b
%...and add this array as a new column to the table
the last assigment in the code above generates this error:
Assigning to 2609 elements using a simple assignment statement is not supported. Consider using comma-separated list assignment.
I don't think I should need a for loop to iterate through each row and replace the value at the "indx" location --what am I doing wrong?
I included the data....thank you.
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Voss
Voss 2024-9-16
Ran in:
newTable = load('data.mat').newTable
newTable = 2609x17 table
LPE_VBAT PEM1_LPE_ZM PEM1_LPE_EXP_GA_CURR PEM1_INVERTER_CURRENT PEM1_GA_Current_Estimate_Error PEM2_LPE_ZM PEM2_LPE_EXP_GA_CURR PEM2_INVERTER_CURRENT PEM2_GA_Current_Estimate_Error PEM3_LPE_ZM PEM3_LPE_EXP_GA_CURR PEM3_INVERTER_CURRENT PEM3_GA_Current_Estimate_Error PEM4_LPE_ZM PEM4_LPE_EXP_GA_CURR PEM4_INVERTER_CURRENT PEM4_GA_Current_Estimate_Error ________ ___________ ____________________ _____________________ ______________________________ ___________ ____________________ _____________________ ______________________________ ___________ ____________________ _____________________ ______________________________ ___________ ____________________ _____________________ ______________________________ 0 0 0 -1.43 NaN 0 0 9.73 NaN 0 0 -0.478 NaN 5.41 129 109 NaN 530 4.21 126 2.62 NaN 4.65 114 46.7 2.4411 0 0 -0.356 NaN 5.06 105 1.97 NaN 530 4.21 126 66.3 1.9005 0 0 -0.343 NaN 0 0 -0.546 NaN 5.06 105 57.7 NaN 531 4.91 108 97.4 1.1088 4.49 118 109 1.0826 0 0 -1.1 NaN 4.19 127 110 NaN 590 4.62 128 -1.27 NaN 5.3 111 65.3 1.6998 0 0 -0.515 NaN 5.26 112 35.8 NaN 535 5.76 93 39.7 2.3426 5.3 101 66.9 1.5097 0 0 -0.171 NaN 5.06 106 3.26 NaN 535 5.76 93 82.1 1.1328 5.3 101 91 1.1099 0 0 -0.222 NaN 0 0 0.454 NaN 524 5.93 88.4 76.3 1.1586 6.45 81.2 73.7 1.1018 0 0 -0.761 NaN 6.25 84 69.8 NaN 589 5.33 110 3.21 NaN 0 0 0.0767 NaN 0 0 -0.152 NaN 4.99 118 36.7 NaN 0 0 0 -1.37 NaN 0 0 5.44 NaN 0 0 -0.0206 NaN 5 138 14.2 NaN 0 0 0 -1.31 NaN 0 0 5.31 NaN 0 0 -0.27 NaN 5.1 136 60.5 NaN 589 4.62 127 87.4 1.4531 4.71 125 85.7 1.4586 0 0 -0.212 NaN 4.82 122 79.9 NaN 0 0 0 -1.61 NaN 4.71 125 85.7 1.4586 0 0 -0.00285 NaN 4.82 122 79 NaN 523 4.6 114 -1.47 NaN 4.6 114 47.8 2.3849 0 0 -0.401 NaN 5.8 90.2 1.99 NaN 597 6.78 88 -1.32 NaN 6.96 85.8 49.5 1.7333 0 0 -0.428 NaN 7.21 82.8 32.7 NaN 597 6.78 88 76.8 1.1458 6.96 85.8 72.6 1.1818 0 0 -0.158 NaN 0 0 0.357 NaN
PEM1b = '0001';
indx = ~isnan(newTable.PEM1_GA_Current_Estimate_Error);
temp = repmat({'0000'},size(newTable,1),1);
temp(indx) = {PEM1b}
temp = 2609x1 cell array
{'0000'} {'0000'} {'0001'} {'0001'} {'0000'} {'0001'} {'0001'} {'0001'} {'0000'} {'0000'} {'0000'} {'0001'} {'0000'} {'0000'} {'0000'} {'0001'} {'0000'} {'0001'} {'0000'} {'0000'} {'0000'} {'0000'} {'0001'} {'0001'} {'0001'} {'0001'} {'0001'} {'0001'} {'0001'} {'0001'}
%...and add this array as a new column to the table
newTable.newColumn = temp
newTable = 2609x18 table
LPE_VBAT PEM1_LPE_ZM PEM1_LPE_EXP_GA_CURR PEM1_INVERTER_CURRENT PEM1_GA_Current_Estimate_Error PEM2_LPE_ZM PEM2_LPE_EXP_GA_CURR PEM2_INVERTER_CURRENT PEM2_GA_Current_Estimate_Error PEM3_LPE_ZM PEM3_LPE_EXP_GA_CURR PEM3_INVERTER_CURRENT PEM3_GA_Current_Estimate_Error PEM4_LPE_ZM PEM4_LPE_EXP_GA_CURR PEM4_INVERTER_CURRENT PEM4_GA_Current_Estimate_Error newColumn ________ ___________ ____________________ _____________________ ______________________________ ___________ ____________________ _____________________ ______________________________ ___________ ____________________ _____________________ ______________________________ ___________ ____________________ _____________________ ______________________________ _________ 0 0 0 -1.43 NaN 0 0 9.73 NaN 0 0 -0.478 NaN 5.41 129 109 NaN {'0000'} 530 4.21 126 2.62 NaN 4.65 114 46.7 2.4411 0 0 -0.356 NaN 5.06 105 1.97 NaN {'0000'} 530 4.21 126 66.3 1.9005 0 0 -0.343 NaN 0 0 -0.546 NaN 5.06 105 57.7 NaN {'0001'} 531 4.91 108 97.4 1.1088 4.49 118 109 1.0826 0 0 -1.1 NaN 4.19 127 110 NaN {'0001'} 590 4.62 128 -1.27 NaN 5.3 111 65.3 1.6998 0 0 -0.515 NaN 5.26 112 35.8 NaN {'0000'} 535 5.76 93 39.7 2.3426 5.3 101 66.9 1.5097 0 0 -0.171 NaN 5.06 106 3.26 NaN {'0001'} 535 5.76 93 82.1 1.1328 5.3 101 91 1.1099 0 0 -0.222 NaN 0 0 0.454 NaN {'0001'} 524 5.93 88.4 76.3 1.1586 6.45 81.2 73.7 1.1018 0 0 -0.761 NaN 6.25 84 69.8 NaN {'0001'} 589 5.33 110 3.21 NaN 0 0 0.0767 NaN 0 0 -0.152 NaN 4.99 118 36.7 NaN {'0000'} 0 0 0 -1.37 NaN 0 0 5.44 NaN 0 0 -0.0206 NaN 5 138 14.2 NaN {'0000'} 0 0 0 -1.31 NaN 0 0 5.31 NaN 0 0 -0.27 NaN 5.1 136 60.5 NaN {'0000'} 589 4.62 127 87.4 1.4531 4.71 125 85.7 1.4586 0 0 -0.212 NaN 4.82 122 79.9 NaN {'0001'} 0 0 0 -1.61 NaN 4.71 125 85.7 1.4586 0 0 -0.00285 NaN 4.82 122 79 NaN {'0000'} 523 4.6 114 -1.47 NaN 4.6 114 47.8 2.3849 0 0 -0.401 NaN 5.8 90.2 1.99 NaN {'0000'} 597 6.78 88 -1.32 NaN 6.96 85.8 49.5 1.7333 0 0 -0.428 NaN 7.21 82.8 32.7 NaN {'0000'} 597 6.78 88 76.8 1.1458 6.96 85.8 72.6 1.1818 0 0 -0.158 NaN 0 0 0.357 NaN {'0001'}

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Stephen23
Stephen23 2024-9-16
编辑：Stephen23 2024-9-16
"I don't think I should need a for loop to iterate through each row and replace the value at the "indx" location"
You do not need a loop, just assign a scalar cell array to the existing cell array using parentheses:
temp(indx) = {PEM1b};
"what am I doing wrong?"
You are trying to assign one array to multiple cells of the cell array. You could think of it something like this:
[a,b,c,d,e,f,..] = pi
While this might be a defined syntax in some languages, with MATLAB this does not assign one array to lots of cells (or variables or fields or ...). In general it is an error. You could use DEAL for some of those situations, but your usecase is actually much simpler: you can use the special case that applies for any array type: a scalar on the RHS will always be expanded to fit the indexing on the LHS into an array of the same type. So all you need is a scalar cell array on the RHS. Which means that the LHS must use parentheses to assign to the cell array itself, not curly braces to replace its content. Then you assign a scalar array element on the RHS to as many elements on the LHS as the indexing specifies (note how I did not write cell, because this concept is exactly the same for every array class).
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Stephen23
Stephen23 2024-9-17
编辑：Stephen23 2024-9-17
Ran in:
"which seemed to work. But I didn't understand why it would...."
Unlike some other languages, type coercion in MATLAB was in the past basically limited to the numeric types and char. For better or for worse, modern users apparently expect type coercion between everything, so the (relatively new) string class can coerce numeric, char, and cell-of-char into strings:
S = "this" % string
S = "this"
S(2) = 'assigns' % char
S = 1x2 string array
"this" "assigns"
S(3) = 3 % numeric
S = 1x3 string array
"this" "assigns" "3"
S(4) = {'types'} % cell of char
S = 1x4 string array
"this" "assigns" "3" "types"
"which to me makes more sense. can you explain what I "did" here?"
You created a string array and then assigned a character vector to it, which got coerced into a string:
T = ["hello";"x"]
T = 2x1 string array
"hello" "x"
T(2) = 'world'
T = 2x1 string array
"hello" "world"
Using a scalar string on the RHS would not use any coercion.

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