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<p class="MsoNormal">Dear all,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-GB">In an r.mapcalc expression, I would like to trace values along a direction map for 1 to n steps (e.g. looking 4 steps ahead along a path or stream or along a given direction (degrees or 45degrees).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I tried using the neighborhood modifier within an eval function in r.mapcalc. Unfortunately, using this command:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">r.mapcalc --o << EOF<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NO-NYN">eval(elev_200 = elevation[1,1] - 200, elev_5 = 5 * elev_200[1,1], elev_p = pow(elev_5, 2))<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">gradient_1 = (0.5 * elev_200) + 0.8 * elev_p<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">EOF<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I get the following error message:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">syntax error, unexpected '[', expecting ')'<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">However, this command works fine:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NO-NYN">r.mapcalc --o << EOF<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="NO-NYN">eval(elev_200 = elevation[1,1] - 200, elev_5 = 5 * elevation[1,1], elev_p = pow(elev_5, 2))<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">gradient_1 = (0.5 * elev_200) + 0.8 * elev_p<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">EOF<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">My questions now are:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">a) is it generally not supported to use the neighbourhood modifier on a temporary map defined in an eval() function in r.mapcalc?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">b) are there other (efficient) approaches for those of us who do not know C (e.g. pygrass)?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">I am grateful for any hint.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Stefan<o:p></o:p></span></p>
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