Hello, i have a table with many rows and 3 columns. In the first column some values are NaN. How can i put NaN values in the other columns in the same rows?

for example

A =

A1 A2 A3

___ __ __

NaN 4 7

NaN 5 8

3 6 9

and I would like to have

A =

A1 A2 A3

___ __ __

NaN NaN NaN

NaN NaN NaN

3 6 9

Answer 1

[Scott MacKenzie]

A{isnan(A{:,1}),2:end} = NaN

Answer 2

[dpb]

Use logical indexing; no loops needed --

>> A{isnan(A.A1),:}=nan
A =
  3×3 table
    A1     A2     A3 
    ___    ___    ___
    NaN    NaN    NaN
    NaN    NaN    NaN
      3      6      9
>> 

NB: the "curlies" to return an array from the indexing operation on the LHS, smooth parens here would return a table instead.

See the documentation for the table class for a detailed exposition on addressing modes and syntax for tables--there's a "veritable plethora" of ways to do so.

Answer 3

[Soniya Jain]

Hey, you can use isnan() function to find the location where values are NaN in the 1st column,

A = [NaN,4,7; NaN,5,8; 3,6,9];
nanV = isnan(A(:,1));
for i=1:height(A)
    if nanV(i,1) == 1
        A(i,:) = NaN;
    end
end