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<div class="moz-cite-prefix">On 11/02/2019 10:42, Tim Sutton wrote:<br>
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<blockquote type="cite"
cite="mid:DF32AB48-3808-47C7-943B-DAA0041867E2@qgis.org">
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Hi<br class="">
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<blockquote type="cite" class="">
<div class="">On 11 Feb 2019, at 10:38, Havard Tveite <<a
href="mailto:havard.tveite@nmbu.no" class=""
moz-do-not-send="true">havard.tveite@nmbu.no</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class=""><span style="caret-color: rgb(0, 0, 0);
font-family: Menlo-Regular; font-size: 14px; font-style:
normal; font-variant-caps: normal; font-weight: normal;
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0px; text-transform: none; white-space: normal;
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!important;" class="">nodata + 1 = nodata</span><br
style="caret-color: rgb(0, 0, 0); font-family:
Menlo-Regular; font-size: 14px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
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0px; text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
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<span style="caret-color: rgb(0, 0, 0); font-family:
Menlo-Regular; font-size: 14px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
letter-spacing: normal; text-align: start; text-indent:
0px; text-transform: none; white-space: normal;
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text-decoration: none; float: none; display: inline
!important;" class="">nodata * 1 = nodata</span><br
style="caret-color: rgb(0, 0, 0); font-family:
Menlo-Regular; font-size: 14px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
letter-spacing: normal; text-align: start; text-indent:
0px; text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration: none;" class="">
<span style="caret-color: rgb(0, 0, 0); font-family:
Menlo-Regular; font-size: 14px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
letter-spacing: normal; text-align: start; text-indent:
0px; text-transform: none; white-space: normal;
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text-decoration: none; float: none; display: inline
!important;" class="">nodata AND 1 = nodata</span><br
style="caret-color: rgb(0, 0, 0); font-family:
Menlo-Regular; font-size: 14px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
letter-spacing: normal; text-align: start; text-indent:
0px; text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration: none;" class="">
<span style="caret-color: rgb(0, 0, 0); font-family:
Menlo-Regular; font-size: 14px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
letter-spacing: normal; text-align: start; text-indent:
0px; text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration: none; float: none; display: inline
!important;" class="">nodata OR 1 = 1</span><br
style="caret-color: rgb(0, 0, 0); font-family:
Menlo-Regular; font-size: 14px; font-style: normal;
font-variant-caps: normal; font-weight: normal;
letter-spacing: normal; text-align: start; text-indent:
0px; text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration: none;" class="">
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<p><br>
</p>
<p>It might be worth noting that in the GRASS mapcalc module,
there's a special operator for these situations. From the manpage:</p>
<ul>
<li>NULL-values in any arithmetic or logical operation should
result
in NULL. (however, &&& and ||| are treated
specially, as described below).
</li>
<li>The &&& and ||| operators observe the following
axioms even when x is NULL:
<div class="code">
<pre> x &&& false == false
false &&& x == false
x ||| true == true
true ||| x == true
</pre>
</div>
</li>
</ul>
<blockquote type="cite"
cite="mid:DF32AB48-3808-47C7-943B-DAA0041867E2@qgis.org">
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<div><br class="">
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<div>Hmm yes, the OR case should return one!</div>
<div><br class="">
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<div>Regards</div>
<div><br class="">
</div>
<div>Tim</div>
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apple-inline="yes"
id="9ED6AE36-FBD9-4A51-8734-503B6CFF0239"
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---</div>
<div style="font-weight: normal;" class=""><br class="">
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<div class=""><b class="">Tim Sutton</b></div>
<div style="font-weight: normal;" class=""><a
href="mailto:tim@qgis.org" class=""
moz-do-not-send="true">tim@qgis.org</a></div>
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<pre class="moz-signature" cols="72">--
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
+972-523-665918</pre>
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