# Customize this starter script by adding code
\n# to the run_script function. See the Help for
\n# complete information on how to create a script
\n# and use Script Runner.<\/p>\n

\u00ab\u00a0\u00a0\u00bb\u00a0\u00bb Your Description of the script goes here \u00ab\u00a0\u00a0\u00bb\u00a0\u00bb<\/p>\n

# Some commonly used imports<\/p>\n

from PyQt4.QtCore import *
\nfrom PyQt4.QtGui import *
\nfrom qgis.core import *
\nfrom qgis.gui import *<\/p>\n

def run_script(iface):
\nqfd = QFileDialog()
\ntitle = ‘Ouvrir un fichier’
\npath = \u00ab\u00a0C:\/\u00a0\u00bb
\nf = QFileDialog.getOpenFileName(qfd, title, path)
\nlayer = QgsVectorLayer(f, \u00ab\u00a0Musees de la ville de New York\u00a0\u00bb, \u00ab\u00a0ogr\u00a0\u00bb)
\nif not layer.isValid():
\nprint \u00ab\u00a0erreur de chargement de la couche %s \u00a0\u00bb % layer.name()
\nQgsMapLayerRegistry.instance().addMapLayers([layer])
\n<\/div><\/div>\n

Remplacez la derni\u00e8re ligne<\/p>\n

QgsMapLayerRegistry.instance().addMapLayers([layer])<\/strong><\/em><\/p>\n

par<\/p>\n

<\/div><\/div>
<\/div><\/div>
features=layer.getFeatures()
\nfeat=features.next()
\ng=feat.geometry()
\nprint g.asPoint()<\/div><\/div>\n
On \u00e9vite de charger la couche dans QGis et on affiche dans la console Python les coordonn\u00e9es x et y du premier point de la couche.<\/p>\n
Le script doit ressembler \u00e0 \u00e7a:<\/p>\n
$\"pv12\"$ <\/a><\/p>\n
La proc\u00e9dure est la suivante:<\/p>\n
features=layer.getFeatures()<\/strong><\/em><\/p>\n
Cr\u00e9e un pointeur nomm\u00e9 features<\/strong> <\/em>sur la couche layer<\/strong><\/em><\/p>\n
feat=features.next()<\/strong><\/em><\/p>\n
On d\u00e9place le curseur sur l’entit\u00e9 suivante, ici c’est la premi\u00e8re entit\u00e9 de la table et on charge cette entit\u00e9 dans l’objet feat<\/strong><\/em>.<\/p>\n
g=feat.geometry()<\/strong><\/em><\/p>\n
Charge la g\u00e9om\u00e9trie de l’entit\u00e9 courante du curseur dans l’objet g<\/strong><\/em>.<\/p>\n
Une fois ex\u00e9cut\u00e9, on obtient le r\u00e9sultat dans la console Python:<\/p>\n
$\"pv13\"$ <\/a>NOTES:<\/strong><\/p>\n
On pourrait acc\u00e9der par d’autres moyens \u00e0 la g\u00e9om\u00e9trie d’une entit\u00e9, mais l’utilisation des pointeurs dans Python permet de travailler sur des volumes de donn\u00e9es tr\u00e8s importants sans charger toute la table en m\u00e9moire.<\/p>\n
Ici on a charg\u00e9 un fichier shapefile, mais quelle qu’elle soit la source de donn\u00e9es, une fois cr\u00e9\u00e9e la couche (layer) le code Python ne change pas.<\/p>\n
Acc\u00e9der aux attributs\u00a0 d’une couche vecteur<\/h2>\n
Pour acc\u00e9der aux attributs non g\u00e9om\u00e9triques des entit\u00e9s, nous allons modifier le script pr\u00e9c\u00e9dent<\/p>\n
Remplacez les deux derni\u00e8res lignes<\/p>\n
g=feat.geometry()<\/strong><\/em>
\n\u00a0 print g.asPoint()<\/strong><\/em><\/p>\n
par<\/p>\n
print feat.attributes()<\/strong><\/em><\/p>\n
Le script doit ressembler \u00e0 \u00e7a:<\/p>\n
$\"pv14\"$ <\/a><\/p>\n
Et son ex\u00e9cution donne le r\u00e9sultat suivant dans la console Python:<\/p>\n
$\"pv15\"$ <\/a><\/p>\n
On obtient bien une liste Python avec l’ensemble des attributs de la premi\u00e8re entit\u00e9 de la table.<\/p>\n
Cette information est g\u00e9n\u00e9ralement reli\u00e9e aux noms des champs de la table. Pour obtenir la liste des noms des champs, remplacez dans le script pr\u00e9c\u00e9dent la ligne<\/p>\n
print feat.attributes()<\/strong><\/em><\/p>\n
par<\/p>\n
print [c.name() for c in feat.fields().toList()]<\/strong><\/em><\/p>\n
Le script doit ressembler \u00e0 \u00e7a:<\/p>\n
$\"pv16\"$ <\/a><\/p>\n
Et son ex\u00e9cution donne le r\u00e9sultat suivant dans la console Python<\/p>\n
$\"pv17\"$ <\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
Une fois une couche charg\u00e9e, on souhaite le plus souvent acc\u00e9der aux donn\u00e9es contenues dans la couche, soit les g\u00e9om\u00e9tries, soit les attributs. Nous verrons ici comment coder en Python l’acc\u00e8s \u00e0 ces deux types de…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"give_campaign_id":0,"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"sfsi_plus_gutenberg_text_before_share":"","sfsi_plus_gutenberg_show_text_before_share":"","sfsi_plus_gutenberg_icon_type":"","sfsi_plus_gutenberg_icon_alignemt":"","sfsi_plus_gutenburg_max_per_row":"","_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[222,62],"tags":[342,232,131,58,223,21],"class_list":["post-3529","post","type-post","status-publish","format-standard","hentry","category-python","category-qgis-2","tag-atribut","tag-geometrie","tag-python","tag-qgis","tag-script","tag-vecteur"],"aioseo_notices":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p6XU0A-UV","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/3529","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/comments?post=3529"}],"version-history":[{"count":0,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/posts\/3529\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/media?parent=3529"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/categories?post=3529"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.sigterritoires.fr\/index.php\/wp-json\/wp\/v2\/tags?post=3529"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}