Returning line before after searching for pattern
显示 更早的评论
I am reading a text file and want to return the line before after encountering search criteria.
The data looks like:
Test 1
X
1
1
1
1
Test 2
X
1
1
1
So I would like to search for X and return the line before.
I was able to return X but not the line before. Thanks!
readfile = readlines(filename); %filename is a .txt file
pat = " X "; %pattern
A = contains(readfile,pat);
display = readfile(A);
采纳的回答
A is a logical array with the same number of rows as the string array readfile. So if you remove/ignore the first element of A, it uses the logical value for row 2 to determine whether or not to select row 1, the logical value for row 3 to determine whether or not to select row 2, etc.
readfile = readlines("sampleText.txt")
pat = "X";
A = contains(readfile,pat)
linesContainingX = readfile(A)
linesBeforeX = readfile(A(2:end))
Note that if the first line of the file matches the pattern, starting your indexing using element 2 of A will skip that line in linesBeforeX; but then again, there isn't a "line before" the first line.
linesContainingTest = contains(readfile, "Test")
linesBeforeContainingTest = readfile(linesContainingTest(2:end))
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Characters and Strings 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
