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<p style="text-align: left;">Dans cet exercice, nous appliquerons <strong>un masque de nuage</strong> aux données Sentinel-2 au large des côtes du Ghana. Les masques des nuages sont importants car ils suppriment les mauvais points de données de notre ensemble de données, afin que nous puissions former une image composite.¶</p>
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<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Comme dans le dernier exercice, nous allons commencer par faire un nouveau notebook Jupyter vierge. Si vous voulez des instructions plus détaillées sur la création d’un nouveau notebook, consultez <a class="reference internal" href="/courses/course-v1:digitalearthafrica+DEA101-fr+2021/jump_to_id/73546668eb4442338866086926025db1" style="box-sizing: border-box; color: #2980b9; text-decoration-line: none; cursor: pointer;" target="[object Object]">cette section dans l’exercice sur le chargement des données dans la Sandbox </a>de la session précédente. Sinon, suivez les étapes ci-dessous.</p>
<ol class="arabic simple" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 24px; padding-left: 0px; list-style-position: initial; list-style-image: initial; line-height: 24px; text-align: left;">
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<p style="text-align: left; box-sizing: border-box; line-height: 24px; margin: 0px; font-size: 16px;">Naviguez vers le dossier <strong style="box-sizing: border-box;">Training</strong> (ou créez ce dossier en suivant les instructions de la <a class="reference internal" href="/courses/course-v1:digitalearthafrica+DEA101-fr+2021/jump_to_id/e42d02bfcd4b40f495c69ad733375ee3" style="box-sizing: border-box; color: #2980b9; text-decoration-line: none; cursor: pointer;" target="[object Object]">Session 1</a>).</p>
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<p style="text-align: left; box-sizing: border-box; line-height: 24px; margin: 0px; font-size: 16px;">Cliquez sur le bouton <strong>+</strong> et cliquez sur <strong>Python 3</strong> dans la section <strong>Notebook</strong>.</p>
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<p style="text-align: left; box-sizing: border-box; line-height: 24px; margin: 0px; font-size: 16px;">Renommez votre fichier pour que vous sachiez qu’il provient de cet exercice. Nous utiliserons ce cahier pour travailler avec les géomédians, alors appelons-le <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">Geomedian_composite.ipynb</span></code>.</p>
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<p style="text-align: left; box-sizing: border-box; line-height: 24px; margin: 0px; font-size: 16px;">Ouvrez le notebook.</p>
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<h3 style="box-sizing: border-box;">Charger des paquets et des fonctions</h3>
<section id="Load-packages-and-functions" style="box-sizing: border-box;">Dans la première cellule, tapez le code suivant, puis exécutez la cellule. Rappelez-vous que les cellules peuvent être exécutées en appuyant sur les touches <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">Shift</span> <span class="pre" style="box-sizing: border-box;">+</span> <span class="pre" style="box-sizing: border-box;">Enter</span></code> de votre clavier.<br /><img alt="image1" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_01_imports.png" style="box-sizing: border-box; border: 0px; vertical-align: middle;" />
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Nous avons utilisé la plupart de ces paquets et fonctions dans l’exercice précédent sur le chargement des données dans le Sandbox . <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">rgb</span></code> permet d’afficher des images en couleur. <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">display_map</span></code> permet de visualiser la zone que nous avons sélectionnée.</p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Dans cette session, nous introduisons deux nouvelles fonctions : <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">load_ard</span></code> <span style="font-size: 11pt; font-family: Arial; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;" id="docs-internal-guid-01b22481-7fff-4ee1-bace-f950e021e82a">et</span> <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">xr_geomedian</span></code>. Nous utiliserons <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">load_ard</span></code> pour charger les données afin qu’elles soient masquées des nuages, et <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">xr_geomedian</span></code> est utilisé dans la section suivante pour calculer le géomédian.</p>
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<h3 style="text-align: left;">Connectez-vous au datacube</h3>
<p style="text-align: left;">Entrez le code suivant et exécutez la cellule pour créer notre objet <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">dc,</span></code> qui donne accès au datacube.<br /><br /></p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;"><img alt="image2" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_02_connect_to_the_datacube.png" style="box-sizing: border-box; border: 0px; vertical-align: middle;" /></p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Votre notebook est maintenant configuré. Ensuite, nous allons charger des données avec des masques des nuages en utilisant <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">load_ard()</span></code>.</p>
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<div class="admonition note" style="text-align: left; box-sizing: border-box; -webkit-font-smoothing: antialiased; padding: 12px; line-height: 24px; margin-bottom: 24px; background: #e7f2fa; color: #000000;">
<p class="admonition-title" style="text-align: left; box-sizing: border-box; line-height: 1; margin: -12px -12px 12px; font-size: inherit; font-family: inherit; font-variant-numeric: normal; font-variant-east-asian: normal; font-weight: bold; font-stretch: normal; text-rendering: auto; -webkit-font-smoothing: antialiased; color: #ffffff; background: #6ab0de; padding: 6px 12px;">Note</p>
<p style="text-align: left; box-sizing: border-box; line-height: 24px; margin: 0px; font-size: 16px;">Si vous rencontrez des erreurs lors de l’exécution des cellules, consultez le guide de code de dépannage de la session précédente.</p>
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<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Intéressons-nous à une zone côtière du Ghana. Entrez le code suivant et exécutez-le pour afficher une carte de la zone. Comme précédemment, <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">x</span></code> désigne la longitude et <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">y</span></code> la latitude.</p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;"><img alt="Example of display_map input and output." class="no-scaled-link" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_displaymap.PNG" style="box-sizing: border-box; border: 0px; vertical-align: middle; width: 700px;" /></p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Dans la nouvelle cellule ci-dessous, entrez le code suivant, puis exécutez-le pour charger les données Sentinel-2. Il générera le texte de sortie <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">Using</span> <span class="pre" style="box-sizing: border-box;">pixel</span> <span class="pre" style="box-sizing: border-box;">quality</span> <span class="pre" style="box-sizing: border-box;">parameters</span> <span class="pre" style="box-sizing: border-box;">for</span> <span class="pre" style="box-sizing: border-box;">Sentinel</span> <span class="pre" style="box-sizing: border-box;">2</span> <span class="pre" style="box-sizing: border-box;">...</span></code>. Le texte de sortie nous indique que nous avons chargé 4 pas de temps.</p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;"><img alt="Using load_ard." class="no-scaled-link" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_loadard.png" style="box-sizing: border-box; border: 0px; vertical-align: middle; width: 700px;" /></p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Prenez note de certaines des différences entre <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">dc.load()</span></code> et <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">load_ard</span></code>.</p>
<ul>
<li><code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">dc=dc</span></code>est un paramètre obligatoire pour <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">load_ard()</span></code>. Cela relie la recherche de données à la connexion du datacube, que nous avons définie dans la configuration du notebook comme <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">dc</span></code>.</li>
<li> Le paramètre pour charger les produits est <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">products</span></code>(pluriel) et non <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">product</span></code> comme dans <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">dc.load()</span></code>.</li>
<li>Les éléments du produit doivent être listés entre crochets <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">[]</span></code>, ce qui n’est pas nécessaire pour <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">dc.load()</span></code>.</li>
<li><code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">min_gooddata</span></code> ssignifie “minimum good data” et écarte les observations dont le nombre de pixels de bonne qualité est inférieur à la fraction requise.<br /><br /></li>
</ul>
<div class="admonition note" style="box-sizing: border-box; -webkit-font-smoothing: antialiased; padding: 12px; line-height: 24px; margin-bottom: 24px; background: #e7f2fa;">
<p class="admonition-title" style="text-align: left; box-sizing: border-box; line-height: 1; margin: -12px -12px 12px; font-size: inherit; font-family: inherit; font-variant-numeric: normal; font-variant-east-asian: normal; font-weight: bold; font-stretch: normal; text-rendering: auto; -webkit-font-smoothing: antialiased; color: #ffffff; background: #6ab0de; padding: 6px 12px;">Note</p>
<p style="text-align: left; box-sizing: border-box; line-height: 24px; margin: 0px; font-size: 16px;"><code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">s2_l2a</span></code> signifie <strong>S</strong>entinel-<strong>2</strong> <strong>L</strong>evel-<strong>2A</strong>. Le quatrième caractère est un “l” alphabétique minuscule. Vérifiez que vous avez saisi le nom du produit correctement pour éviter les erreurs.</p>
</div>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Nous pouvons utiliser le même code d’affichagee <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">rgb</span></code> ue dans la dernière session pour afficher une image RVB d’un des pas de temps. Commençons par le premier pas de temps, qui a un <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">index</span></code> de <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">0</span></code>.</p>
<p style="text-align: left; box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px;"><img alt="Plotting an RGB of the first timestep." class="no-scaled-link" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_cloudmask1.png" style="box-sizing: border-box; border: 0px; vertical-align: middle; width: 700px;" /></p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Cela devrait produire une seule image RVB comme indiqué ci-dessous. Que se passe-t-il si vous essayez de changer le numéro <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">index</span></code> ?</p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; text-align: left;"><img alt="Output RGB of the first timestep." class="no-scaled-link" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_rgbout.PNG" style="box-sizing: border-box; border: 0px; vertical-align: middle; width: 550px;" /></p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Si nous voulons voir les images RVB de tous les pas de temps en une seule fois, nous pouvons remplacer le paramètre <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">index</span></code> par le paramètre <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">col</span></code> . signifie “colonne”. En spécifiant <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">col='time'</span></code> , on crée une ligne d’images pour les pas de temps.</p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;"><img alt="Plotting RGBs of all timestep." class="no-scaled-link" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_cloudmask2.png" style="box-sizing: border-box; border: 0px; vertical-align: middle; width: 700px;" /></p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">La sortie devrait ressembler à ceci.</p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;"><img alt="Output RGBs from col=time." class="no-scaled-link" src="https://learn.digitalearthafrica.org/asset-v1:digitalearthafrica+DEA101+2021+type@asset+block@02_cloud_masking_colout.PNG" style="box-sizing: border-box; border: 0px; vertical-align: middle; width: 800px;" /></p>
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<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Bon travail - vous avez maintenant chargé des données en utilisant <code class="docutils literal notranslate" style="box-sizing: border-box; font-family: SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', 'Courier New', Courier, monospace; font-size: 12px; white-space: nowrap; max-width: 100%; background-image: initial; background-color: #ffffff; border: 1px solid #e1e4e5; padding: 2px 5px; color: #e74c3c; overflow-x: auto;"><span class="pre" style="box-sizing: border-box;">load_ard()</span></code>, qui a un masque automatique de nuages. Nous pouvons voir que les images à différents moments ont une couverture nuageuse différente, donc elles ont été masquées à différents endroits. C’est pourquoi le fait d’avoir des données à différents intervalles de temps peut nous permettre de créer une image composite sans aucun nuage.</p>
<p style="box-sizing: border-box; line-height: 24px; margin: 0px 0px 24px; font-size: 16px; text-align: left;">Dans la section suivante, nous utiliserons ces données chargées pour créer un composite géomédian.</p>
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