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how extract table RowNames based on table elements

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Yunwei
Yunwei 2023-2-22
回答： Steven Lord 2023-2-22
Hello all,
I have a table of only one colume with RowNames.
The table have numerical values and NaN.
I want to extract the RowNames of all of the NaN in the table. How can I do that?
Thanks in advance!

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采纳的回答

Voss
Voss 2023-2-22
Ran in:
% a table as you describe
t = table([1;NaN;3;4;NaN],'RowNames',{'A';'B';'C';'D';'E'})
t = 5×1 table
Var1 ____ A 1 B NaN C 3 D 4 E NaN
% extract RowNames of the NaN rows
nan_rows = t.Properties.RowNames(isnan(t{:,:}))
nan_rows = 2×1 cell array
{'B'} {'E'}

更多回答（1 个）

Steven Lord
Steven Lord 2023-2-22
Ran in:
I'd use ismissing, to avoid the need to extract the whole contents of the table into a separate array.
% a table as you describe
t = table([1;NaN;3;4;NaN],'RowNames',{'A';'B';'C';'D';'E'})
t = 5×1 table
Var1 ____ A 1 B NaN C 3 D 4 E NaN
% extract RowNames of the NaN rows
nan_rows = t.Properties.RowNames(ismissing(t))
nan_rows = 2×1 cell array
{'B'} {'E'}
This also works if t has variables of different types. Yes, I could have listed "elderberry" but I need a missing value for the example.
t.FruitNames = ["apple"; "banana"; "cherry"; "date"; missing]
t = 5×2 table
Var1 FruitNames ____ __________ A 1 "apple" B NaN "banana" C 3 "cherry" D 4 "date" E NaN <missing>
ismissing(t)
ans = 5×2 logical array
0 0 1 0 0 0 0 0 1 1
rowWithMissingNumberAndFruit = t.Properties.RowNames(all(ismissing(t), 2))
rowWithMissingNumberAndFruit = 1×1 cell array
{'E'}
rowWithMissingNumberOrFruit = t.Properties.RowNames(any(ismissing(t), 2))
rowWithMissingNumberOrFruit = 2×1 cell array
{'B'} {'E'}
The approach Voss posted wouldn't work here.
isnan(t{:,:})
Incorrect number or types of inputs or outputs for function 'isnan'.

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