Reading a massive file but skipping several lines / rows at a fixed interval

4 visualizaciones (últimos 30 días)
What is the most efficient way to read / analyze rows 1-1990 of an array, then skip 9 lines, then read rows 2000-3990, skip 9 rows, read rows 4000-5990, and so on to the end of the array? Is there a way to vectorize that?
  5 comentarios
L'O.G.
L'O.G. el 29 de Mzo. de 2022
Yes, but how? I know how to delete every 4th row, for example, would be A(4:4:end,:) = [] but I don't know how to apply that for my case where I need to skip / delete multiply lines.
Stephen23
Stephen23 el 29 de Mzo. de 2022
Editada: Stephen23 el 29 de Mzo. de 2022
Use a loop. Inside the loop you can easily tell MATLAB which part of the file to read, e.g.:
  • TEXTSCAN lets you specify how many times the format is applied and how many header lines.
  • READTABLE et al let you specify the data location, header location, etc.
What is so special about the rows you wan to ignore: are they intermediate headers or just data you don't want? The answer to that question will change how you can approach this task.

Iniciar sesión para comentar.

Respuesta aceptada

KSSV
KSSV el 29 de Mzo. de 2022
Editada: KSSV el 29 de Mzo. de 2022
id = 1:9 ; % line numbers
V = 1990:2000:9990 ; % give the end wisely
idx = id'+V ; % make indices
idx = idx(:) ; % make indices a column
% Let A be your array
A(idx) = [] ; % remove the lines using the indices
  2 comentarios
L'O.G.
L'O.G. el 29 de Mzo. de 2022
Thanks. Very nice. One small typo: the last line should be: A(idx,:) = [];
KSSV
KSSV el 29 de Mzo. de 2022
Yes, if it is an array use A(idx), if it is a matrix, A(idx,:). I have considered it as an array. :)

Iniciar sesión para comentar.

Más respuestas (1)

Arif Hoq
Arif Hoq el 29 de Mzo. de 2022
try this loop:
A=(1:9990)'; % making an array
idx=2000; % taken value from 2000
count=(size(A,1)+10)/idx;
first_index=A(1:1990); % first index value to make the loop simple
C=cell(count,1);
for i=2:count
C{i}=A(idx*(i-1):(idx*i)-10);
end
mat=[C{:}]

Categorías

Más información sobre Logical en Help Center y File Exchange.

Productos


Versión

R2021b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by