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1 ## Copyright (C) 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2002, 2004, |
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2 ## 2005, 2006, 2007 John W. Eaton |
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3 ## |
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4 ## This file is part of Octave. |
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5 ## |
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6 ## Octave is free software; you can redistribute it and/or modify it |
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7 ## under the terms of the GNU General Public License as published by |
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8 ## the Free Software Foundation; either version 3 of the License, or (at |
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9 ## your option) any later version. |
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10 ## |
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11 ## Octave is distributed in the hope that it will be useful, but |
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12 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 ## General Public License for more details. |
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15 ## |
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16 ## You should have received a copy of the GNU General Public License |
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17 ## along with Octave; see the file COPYING. If not, see |
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18 ## <http://www.gnu.org/licenses/>. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} stairs (@var{x}, @var{y}) |
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22 ## Produce a stairstep plot. The arguments may be vectors or matrices. |
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23 ## |
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24 ## If only one argument is given, it is taken as a vector of y-values |
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25 ## and the x coordinates are taken to be the indices of the elements. |
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26 ## |
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27 ## If two output arguments are specified, the data are generated but |
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28 ## not plotted. For example, |
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29 ## |
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30 ## @example |
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31 ## stairs (x, y); |
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32 ## @end example |
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33 ## |
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34 ## @noindent |
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35 ## and |
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36 ## |
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37 ## @example |
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38 ## @group |
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39 ## [xs, ys] = stairs (x, y); |
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40 ## plot (xs, ys); |
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41 ## @end group |
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42 ## @end example |
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43 ## |
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44 ## @noindent |
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45 ## are equivalent. |
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46 ## @seealso{plot, semilogx, semilogy, loglog, polar, mesh, contour, |
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47 ## bar, xlabel, ylabel, title} |
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48 ## @end deftypefn |
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49 |
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50 ## Author: jwe |
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51 |
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52 function [xs, ys] = stairs (x, y) |
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53 |
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54 if (nargin < 1 || nargin > 2) |
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55 print_usage (); |
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56 endif |
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57 |
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58 if (nargin == 1) |
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59 if (ismatrix (x)) |
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60 if (isvector (x)) |
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61 x = x(:); |
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62 endif |
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63 y = x; |
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64 x = 1:rows (y); |
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65 endif |
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66 endif |
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67 |
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68 if (ndims (x) > 2 || ndims (y) > 2) |
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69 error ("stairs: expecting 2-d arguments"); |
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70 endif |
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71 |
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72 vec_x = isvector (x); |
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73 |
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74 if (vec_x) |
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75 x = x(:); |
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76 endif |
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77 |
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78 if (isvector (y)) |
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79 y = y(:); |
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80 endif |
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81 |
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82 if (ismatrix (y)) |
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83 [nr, nc] = size (y); |
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84 if (vec_x) |
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85 x = repmat (x, [1, nc]); |
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86 else |
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87 [x_nr, x_nc] = size (x); |
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88 if (x_nr != nr || x_nc != nc) |
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89 error ("stairs: argument size mismatch"); |
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90 endif |
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91 endif |
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92 endif |
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93 |
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94 len = 2*nr - 1; |
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95 |
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96 tmp_xs = tmp_ys = zeros (len, nc); |
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97 |
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98 tmp_xs(1,:) = x(1,:); |
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99 tmp_ys(1,:) = y(1,:); |
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100 |
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101 tmp_x = x(2:nr,:); |
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102 ridx = 2:2:len-1; |
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103 tmp_xs(ridx,:) = tmp_x; |
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104 tmp_ys(ridx,:) = y(1:nr-1,:); |
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105 |
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106 ridx = 3:2:len; |
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107 tmp_xs(ridx,:) = tmp_x; |
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108 tmp_ys(ridx,:) = y(2:nr,:); |
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109 |
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110 if (nargout == 0) |
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111 plot (tmp_xs, tmp_ys); |
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112 else |
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113 xs = tmp_xs; |
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114 ys = tmp_ys; |
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115 endif |
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116 |
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117 endfunction |
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118 |
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119 %!demo |
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120 %! x = 1:10; |
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121 %! y = rand (1, 10); |
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122 ## stairs (x, y); |
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123 |
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124 %!demo |
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125 %! x = 1:10; |
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126 %! y = rand (1, 10); |
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127 %! [xs, ys] = stairs (x, y); |
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128 %! plot (xs, ys); |
