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    <p>Hi,</p>
    <p>may be it will be easier to use thhis algorithm: "Add geometry
      attributes" ->
<a class="moz-txt-link-freetext" href="https://docs.qgis.org/3.10/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html?highlight=exportaddgeometrycolumns#add-geometry-attributes">https://docs.qgis.org/3.10/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html?highlight=exportaddgeometrycolumns#add-geometry-attributes</a></p>
    <p>best regards</p>
    <p>Stefan<br>
    </p>
    <div class="moz-cite-prefix">Am 30.01.2023 um 14:13 schrieb Igor
      Oliveira Ribeiro via QGIS-User:<br>
    </div>
    <blockquote type="cite"
cite="mid:CACruqLAr8iSdEWEhad4vjYFvUbVZ-bXg-tcBJW5KdS1cvGuhRQ@mail.gmail.com">
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        <div class="gmail_default"
          style="font-family:arial,helvetica,sans-serif;font-size:small">Hi
          community, </div>
        <div class="gmail_default"
          style="font-family:arial,helvetica,sans-serif;font-size:small">I
          need your help. I'm using QGIS 3.10.11 with Grass 7.8.4. I'm
          building a QGIS modeler and I want to calculate the area of an
          input polygon.</div>
        <div class="gmail_default"
          style="font-family:arial,helvetica,sans-serif;font-size:small"><br>
        </div>
        <div class="gmail_default"
          style="font-family:arial,helvetica,sans-serif;font-size:small">So,
          my input polygon is a vector feature. I tried using a field
          calculator ($area) and Advanced Python Field Calculator (Field
          "Formula", I used "value = $geom.area() ).</div>
        <div class="gmail_default"
          style="font-family:arial,helvetica,sans-serif;font-size:small"><br>
        </div>
        <div class="gmail_default"
          style="font-family:arial,helvetica,sans-serif;font-size:small">However,
          nothing is working. When I run the modeler, there is no error
          message. But, I'dont have the area calculated either.</div>
        <div class="gmail_default"
          style="font-family:arial,helvetica,sans-serif;font-size:small"><br>
        </div>
        <div>
          <div class="gmail_default"
            style="font-family:arial,helvetica,sans-serif;font-size:small">Thanks
            for your help.</div>
          <br>
        </div>
        -- <br>
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                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><a
href="https://doi.org/10.1016/j.envpol.2020.114029" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Arial;color:rgb(39,78,19);font-weight:700;font-style:italic;vertical-align:baseline;white-space:pre-wrap">See our last paper: </span></a></p>
                                          <p dir="ltr"
                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><a
href="https://doi.org/10.1016/j.envpol.2020.114029" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Arial;color:rgb(0,0,0);font-style:italic;vertical-align:baseline;white-space:pre-wrap">Impact of biomass burning on a metropolitan area in the Amazon during the 2015 El Niño: The enhancement of carbon monoxide and levoglucosan concentrations.</span></a></p>
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                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:11pt;font-family:Arial;color:rgb(0,0,0);background-color:transparent;vertical-align:baseline;white-space:pre-wrap"><span style="border:none;display:inline-block;overflow:hidden;width:146px;height:145px"><img src="https://lh5.googleusercontent.com/-bliIGlTBH64UHBAAns8Ubhxgih0cgNVZjNAWPkBZSkYIa-o9idb3Km_x571oZ3NL0nZVMvFmclRedyzJDfv00BMdZPjcKg4zD1y1yGGErKoPszFJuTRjvN_0fmLsa4Ah_2YTtxJ" style="margin-left:0px;margin-top:0px" moz-do-not-send="true" width="146" height="145"></span></span></p>
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                                          <p dir="ltr"
                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:12pt;font-family:Georgia;color:rgb(56,118,29);background-color:transparent;font-weight:700;vertical-align:baseline;white-space:pre-wrap">Igor Oliveira Ribeiro</span></p>
                                          <p dir="ltr"
                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:8pt;font-family:Georgia;color:rgb(0,0,0);font-style:italic;vertical-align:baseline;white-space:pre-wrap">Post-Doc on Regional Climate Change, Vulnerability, Impacts and Adaptation - Cuomo Foundation/UEA</span></p>
                                          <br>
                                          <p dir="ltr"
                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:8pt;font-family:Georgia;color:rgb(34,34,34);vertical-align:baseline;white-space:pre-wrap">+55 92 98103 7136 | skype: igorflorestal</span></p>
                                          <br>
                                          <p dir="ltr"
                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:8pt;font-family:Georgia;color:rgb(34,34,34);vertical-align:baseline;white-space:pre-wrap">Universidade do Estado do Amazonas | Instituto Nacional de Pesquisas da Amazônia</span></p>
                                          <br>
                                          <p dir="ltr"
                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><span style="font-size:8pt;font-family:Georgia;color:rgb(34,34,34);vertical-align:baseline;white-space:pre-wrap">Visite: </span><a
href="http://www.geoescrita.com.br" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Georgia;color:rgb(56,118,29);vertical-align:baseline;white-space:pre-wrap">www.geoescrita.com.br</span></a></p>
                                          <br>
                                          <p dir="ltr"
                                            style="line-height:1.2;margin-top:0pt;margin-bottom:0pt"><a
href="https://www.linkedin.com/in/igoroliveiraribeiro/" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Georgia;color:rgb(17,85,204);vertical-align:baseline;white-space:pre-wrap"><span style="border:none;display:inline-block;overflow:hidden;width:27px;height:27px"><img src="https://lh4.googleusercontent.com/2py0KXy5JccNXFC-38-2TT9wnYCQAXMRBlM5H0eOS83jy2Sz-PUr9_1C57srnad478ma9o9_fAYHjUhFN7Hza3OOCSiFHFpboznBl1PpVLavbfnjGYoU1usFc0W8j9pS4VzAKwCV" style="margin-left:0px;margin-top:0px" moz-do-not-send="true" width="27" height="27"></span></span></a><a
href="https://www.instagram.com/geoescrita/" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Georgia;color:rgb(17,85,204);vertical-align:baseline;white-space:pre-wrap"><span style="border:none;display:inline-block;overflow:hidden;width:27px;height:27px"><img src="https://lh4.googleusercontent.com/-FUMJ4HbrYAwwTKB49CF6r39wVYnoWf1AD9ZLKvD6Z1Cu1yqyo8NRk-InWHOa34J87OHDcJcCstkC_khG2_jCc6qDGop64cV2F0OL-IZ1S3Jgf9SfxVF08U9xfx47ov24InhjsqE" style="margin-left:0px;margin-top:0px" moz-do-not-send="true" width="27" height="27"></span></span></a><a
href="https://www.researchgate.net/profile/Igor_Oliveira_Ribeiro"
                                              target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Georgia;color:rgb(17,85,204);vertical-align:baseline;white-space:pre-wrap"><span style="border:none;display:inline-block;overflow:hidden;width:27px;height:27px"><img src="https://lh6.googleusercontent.com/ert1Bk_3idA2Vb4MK8Hd3B1p2vdcL52JrOmNjaGhhbS7caCNQiZwRKKX55B9pB7-3j2nPFttXJezhSxrHQeBpnEnpeD_CRjzBQgPo5hG5C68qhY1wRFMu0PDv9LbQ8iY8-K4bwIk" style="margin-left:0px;margin-top:0px" moz-do-not-send="true" width="27" height="27"></span></span></a><a
href="http://lattes.cnpq.br/3909691804095045" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Georgia;color:rgb(17,85,204);vertical-align:baseline;white-space:pre-wrap"><span style="border:none;display:inline-block;overflow:hidden;width:27px;height:27px"><img src="https://lh6.googleusercontent.com/z9emf1sj2DW-tYYJZ6Qkd3RxvB23DjQdH7bLcTDIv9zyi-XnZRAroZBc8OPJqQkDIvZJBpd7GCa-2ClAT2gT3ubJ4yZj1BA0-T8hGgBboms-kjpowUuhBQO4z4EcWDwF9w25FGiy" style="margin-left:0px;margin-top:0px" moz-do-not-send="true" width="27" height="27"></span></span></a><a
href="https://orcid.org/0000-0002-3529-0525" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Georgia;color:rgb(17,85,204);vertical-align:baseline;white-space:pre-wrap"><span style="border:none;display:inline-block;overflow:hidden;width:27px;height:27px"><img src="https://lh4.googleusercontent.com/fOmYAxdij-Q_UFG3dFFnhy_zegLQSPZcgxSE-l8u9XuSz6LvnUGItsmoPZL_GCcfoYF2yl9dqYGs3842AcozPLqY103OWAe1x-js_lNLXym1Wcde7j4r19_vICiJXP5xaE_-KPIL" style="margin-left:0px;margin-top:0px" moz-do-not-send="true" width="27" height="27"></span></span></a><a
href="https://www.geoescrita.com.br/" target="_blank"
                                              moz-do-not-send="true"><span style="font-size:8pt;font-family:Georgia;color:rgb(17,85,204);vertical-align:baseline;white-space:pre-wrap"><span style="border:none;display:inline-block;overflow:hidden;width:27px;height:27px"><img src="https://lh3.googleusercontent.com/H041znsV0LChyhfdBIDwXHwIh5BUG2TCmQYBSI1d4eF1NX80_T79MtdQqif3DHpBIDgzvXhuXDLc0l77eylJCPuW7jbalTIbVqBg-dm8S-JHOxZh458R0UX8SsJINhcqw7nG7_Pw" style="margin-left:0px;margin-top:0px" moz-do-not-send="true" width="27" height="27"></span></span></a></p>
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