Mercurial > hg > octave-terminal
changeset 3666:301e0da5b455
[project @ 2000-05-13 06:02:36 by jwe]
author | jwe |
---|---|
date | Sat, 13 May 2000 06:03:55 +0000 |
parents | 0689afb1d001 |
children | f7f94396dd81 |
files | scripts/ChangeLog scripts/strings/strrep.m |
diffstat | 2 files changed, 45 insertions(+), 19 deletions(-) [+] |
line wrap: on
line diff
--- a/scripts/ChangeLog +++ b/scripts/ChangeLog @@ -1,3 +1,11 @@ +2000-05-13 John W. Eaton <jwe@bevo.che.wisc.edu> + + * strings/strrep.m: Don't transpose result for case of jump > 0. + +2000-05-13 Paul Kienzle <pkienzle@kienzle.powernet.co.uk> + + * strings/strrep.m: Avoid for loop for speed. + 2000-04-04 John Smith <john@arrows.demon.co.uk> * statistics/distributions/beta_inv.m: Provide better(?) initial
--- a/scripts/strings/strrep.m +++ b/scripts/strings/strrep.m @@ -34,7 +34,7 @@ function t = strrep (s, x, y) - if (nargin <> 3) + if (nargin != 3) usage ("strrep (s, x, y)"); endif @@ -48,25 +48,43 @@ endif ind = findstr (s, x, 0); - len = length (ind); - if (len == 0) + + if (length(ind) == 0) t = s; - else - save_empty_list_elements_ok = empty_list_elements_ok; - unwind_protect - empty_list_elements_ok = 1; - l_x = length (x); - tmp = s (1 : ind (1) - 1); - t = strcat (tmp, y); - for k = 1 : len - 1 - tmp = s (ind (k) + l_x : ind (k+1) - 1); - t = strcat (t, tmp, y); - endfor - tmp = s (ind(len) + l_x : length (s)); - t = [t, tmp]; - unwind_protect_cleanup - empty_list_elements_ok = save_empty_list_elements_ok; - end_unwind_protect + elseif (length(y) > 0) # replacement + ## Copy the parts of s that aren't being replaced. This is done + ## with an index vector, with jumps where each search string + ## is found. For a jump of 0 (target length == replacement length) + ## the index is just cumsum ( ones (length (s))). For non-zero + ## jumps, add the jump size to the ones vector at each found position. + jump = length(y) - length(x); + if (jump > 0) # s expands + di = ones(size(s)); + di (ind) = 1 + jump * ones (length (ind), 1); + t (cumsum (di)) = s + elseif (jump < 0) # s contracts + di = ones (jump * length (ind) + length (s), 1); + di (ind + jump * [0:length(ind)-1]) = 1 - jump * ones(length(ind), 1); + t = s (cumsum (di)); + else # s stays the same length + t = s; + endif + ## Now, substitute a copy of the replacement string whereever the + ## search string was found. Note that we must first update the + ## target positions to account for any expansion or contraction + ## of s that may have occurred. + ind = ind + jump * [ 0 : length (ind) - 1 ]; + repeat = [1 : length (y)]' * ones (1, length (ind)); + dest = ones (length (y), 1) * ind + repeat - 1; + t (dest) = y (repeat); + else # deletion + ## Build an index vector of all locations where the target was found + ## in the search string, and zap them. + t = toascii(s); + repeat = [1:length(x)]' * ones (1, length (ind)); + delete = ones (length (x), 1) * ind + repeat - 1; + t (delete) = []; + t = setstr(t); endif endfunction