Saving a vector layer as .xyz with PyQGIS 3

Question

I'm writing a standalone script for QGIS. In this script I want to import a couple of text files saved as .xyz. When I import them in QGIS I have to use "Import layers as delimited text", thus they are not rasters. They are text files with lots of rows and each row contains x,y and z coordinates.

After I import them I want to check a condition and export them to a new folder. The import part works fine but I get no export files in my output folder. That's the export part of the script:

lyr = QgsVectorLayer(uri, name, "delimitedtext")
outDir = 'C:/Users/user/Desktop/output'
fields = lyr.fields()
QgsVectorFileWriter.writeAsVectorFormat(lyr, outDir, "utf-8", fields, "CSV",
                                        layerOptions=['GEOMETRY=AS_XYZ'])

When I try to run the script, I don't get an error message but there are also no files in my output folder. I don't see the error. Can someone help me?

I'm using QGIS 3.4.13

EDIT

I checked the answers and modified the code but it is still not working. Still no error message and still no files in my output folder.

This is the whole function without the condition:

def moveFiles(self):
    inputDir = self.dlg.input_folder.text() #directory of xyz files - "Users/denni/Desktop/xyz_data"
    outDir = self.dlg.output_folder.text()  #output directory - "C:/Users/denni/Desktop/output/"
    crs = "EPSG:25832"

    for file in glob.glob("*.xyz"):
        uri = "file:///" + inputDir +"/"+ file + "?type=csv&delimiter=%s&crs=%s&xField=%s&yField=%s" % (" ", crs, "field_1", "field_2")
        name = file.replace('.xyz', '')
        lyr = QgsVectorLayer(uri, name, "delimitedtext")
        outputPath = outDir + file
        QgsVectorFileWriter.writeAsVectorFormat(lyr, outputPath, 'utf-8', lyr.crs(), "CSV",
                                                layerOptions='GEOMETRY=AS_XYZ')

What could be the problem?

Answer 1

There are various issues here. A correction below (tested before answering)

import os
from urllib.parse import urlparse

# URI should contain the path from your existing file not where you want to write
# Your extension must be csv (ps: tested with xyz extension and fails later)
uri = 'file:///home/thomasg/csv-pyqgis/points_xyz.csv?type=csv&detectTypes=yes&xField=x&yField=y&zField=z&crs=EPSG:4326&spatialIndex=yes&subsetIndex=no&watchFile=no'

lyr = QgsVectorLayer(uri, 'myname', "delimitedtext")
filename = urlparse(uri).path.split(os.path.sep)[-1].replace('.xyz', '.csv')
outDir = '/tmp/output'
# Create dir if not present
if not os.path.isdir(outDir):
    os.mkdir(outDir)

# Change arguments to match allowed signature of the function
# output path changed by concatenating directory output and file
# This path is where you want to write content
outfilepath = os.path.join(outDir, filename)
QgsVectorFileWriter.writeAsVectorFormat(lyr, outfilepath, 'utf-8', lyr.crs(), "CSV", layerOptions=['GEOMETRY=AS_XYZ'])

Answer 2

writeAsVectorFormat method has three different usages. Your code match none of them. The code is correct syntactically, but incorrect logically. Your code matchs QgsVectorFileWriter constructor method.

lyr = QgsVectorLayer(uri, name, "delimitedtext")

outFilePath = 'C:/Users/user/Desktop/output/filename'

QgsVectorFileWriter.writeAsVectorFormat(lyr,
                                        outFilePath,
                                        "utf-8",
                                        driverName="CSV",
                                        layerOptions=['GEOMETRY=AS_XYZ'])

Then change filename.csv into filename.xyz.

Note: Since you specified driverName as CSV, the last text in the path (/filename) will be considered as a file name, not a directory. And the layer will be saved as filename.csv.