Taking control of charts in SPSS

2013-11-03

Below is an example script that draws simple bar charts. It was the only acceptable way for me to programmatically generate charts in SPSS. There is something to note here - this solution needs three distinct scripting languages:

  1. The script is written in Python - which is integrated in SPSS 22. For older versions you need a Python plugin.
  2. The code in SpssClient.RunSyntax call is in SPSS Command Syntax.
  3. The code between BEGIN GPL and END GPL is in Graphics Production Language (GPL).
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import SpssClient
import string
import xml.etree.ElementTree as ET

SpssClient.StartClient()
print("Started.")

SpssClient.RunSyntax(r"""
GET FILE="D:\mydata.sav".
DATASET NAME mydata.
""")

def draw_chart_bars(id, column, dataset):
    SpssClient.RunSyntax(string.Template(r"""
    GGRAPH
        /GRAPHDATASET NAME="${id}" DATASET=${dataset} VARIABLES=${column} REPORTMISSING=YES
        /GRAPHSPEC SOURCE=INLINE.
    BEGIN GPL
        SOURCE: s=userSource(id("${id}"))
        DATA: d=col(source(s), name("${column}"), unit.category())
        GUIDE: axis(dim(2), gridlines())
        ELEMENT: interval(position(summary.count(d)))
    END GPL.
    """).substitute(locals()))

def export_chart(id, filename):
    OutputDoc = SpssClient.GetDesignatedOutputDoc()
    OutputItems = OutputDoc.GetOutputItems()
    for index in range(OutputItems.Size()):
        OutputItem = OutputItems.GetItemAt(index)
        if OutputItem.GetType() == SpssClient.OutputItemType.CHART:
            ChartItem = OutputItem.GetSpecificType()
            root = ET.fromstring(OutputItem.GetXML())
            source = root.find(".//*[@id='d']")
            if id == source.attrib['source']:
                OutputItem.ExportToImage(filename, SpssClient.ChartExportFormat.png)

for column in ["color", "brand"]:
    draw_chart_bars(column = column, dataset = "mydata", id = "mychart" + column)
    export_chart(filename = "D:/" + column + ".png", id = "mychart" + column)
    print("Done: " + column)

SpssClient.StopClient()
print("Finished.")

P.S. Yes, I am aware of a performance bug in export_chart function where it parses the XMLs of each OutputItem.