使用 Python 在演示文稿中管理图表数据标签
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简介
图表上的数据标签显示有关图表数据系列或单个数据点的详细信息。它们可以让读者快速识别数据系列，并使图表更易于理解。
设置图表数据标签的数据精度
下面的 Python 代码演示如何在图表数据标签中设置数据精度：
import jpype
import asposeslides
if not jpype.isJVMStarted():
jpype.startJVM()
from asposeslides.api import ChartType, Presentation, SaveFormat
presentation = Presentation()
try:
chart = presentation.getSlides().get_Item(0).getShapes().addChart(ChartType.Line, 50, 50, 450, 300)
chart.setDataTable(True)
chart.getChartData().getSeries().get_Item(0).setNumberFormatOfValues("#,##0.00")
presentation.save("output.pptx", SaveFormat.Pptx)
finally:
presentation.dispose()
将百分比显示为标签
Aspose.Slides for Python via Java 允许在显示的图表上设置百分比标签。下面的 Python 代码演示此操作：
import jpype
import asposeslides
if not jpype.isJVMStarted():
jpype.startJVM()
from asposeslides.api import ChartType, Portion, Presentation, SaveFormat
presentation = Presentation()
try:
slide = presentation.getSlides().get_Item(0)
chart = slide.getShapes().addChart(ChartType.StackedColumn, 20, 20, 400, 400)
chart_series = chart.getChartData().getSeries()
category_totals = [0.0] * chart.getChartData().getCategories().size()
for category_index in range(len(category_totals)):
for series_index in range(chart_series.size()):
data_point = chart_series.get_Item(series_index).getDataPoints().get_Item(category_index)
category_totals[category_index] += float(data_point.getValue().getData())
for series_index in range(chart_series.size()):
series = chart_series.get_Item(series_index)
series.getLabels().getDefaultDataLabelFormat().setShowLegendKey(False)
for point_index in range(series.getDataPoints().size()):
data_point = series.getDataPoints().get_Item(point_index)
label = data_point.getLabel()
if category_totals[point_index] == 0:
print(f"Cannot calculate a percentage for category {point_index}: the total is zero.")
continue
point_percentage = float(data_point.getValue().getData()) / category_totals[point_index] * 100
portion = Portion()
portion.setText(f"{point_percentage:.2f} %")
portion.getPortionFormat().setFontHeight(8)
label.getTextFrameForOverriding().setText("")
paragraph = label.getTextFrameForOverriding().getParagraphs().get_Item(0)
paragraph.getPortions().add(portion)
label_format = label.getDataLabelFormat()
label_format.setShowSeriesName(False)
label_format.setShowPercentage(False)
label_format.setShowLegendKey(False)
label_format.setShowCategoryName(False)
label_format.setShowBubbleSize(False)
presentation.save("output.pptx", SaveFormat.Pptx)
finally:
presentation.dispose()
在图表数据标签中设置百分号
下面的 Python 代码演示如何为图表数据标签设置百分号：
import jpype
import asposeslides
if not jpype.isJVMStarted():
jpype.startJVM()
from asposeslides.api import ChartType, FillType, Presentation, SaveFormat
Color = jpype.JClass("java.awt.Color")
presentation = Presentation()
try:
slide = presentation.getSlides().get_Item(0)
chart = slide.getShapes().addChart(ChartType.PercentsStackedColumn, 20, 20, 500, 400)
chart.getAxes().getVerticalAxis().setNumberFormatLinkedToSource(False)
chart.getAxes().getVerticalAxis().setNumberFormat("0.00%")
chart.getChartData().getSeries().clear()
worksheet_index = 0
workbook = chart.getChartData().getChartDataWorkbook()
# 添加红色系列。
series_cell = workbook.getCell(worksheet_index, 0, 1, "Reds")
red_series = chart.getChartData().getSeries().add(series_cell, chart.getType())
for row_index, value in enumerate([0.30, 0.50, 0.80, 0.65], start=1):
data_cell = workbook.getCell(worksheet_index, row_index, 1, jpype.JDouble(value))
red_series.getDataPoints().addDataPointForBarSeries(data_cell)
red_series.getFormat().getFill().setFillType(FillType.Solid)
red_series.getFormat().getFill().getSolidFillColor().setColor(Color.RED)
red_label_format = red_series.getLabels().getDefaultDataLabelFormat()
red_label_format.setShowValue(True)
red_label_format.setNumberFormatLinkedToSource(False)
red_label_format.setNumberFormat("0.0%")
red_portion_format = red_label_format.getTextFormat().getPortionFormat()
red_portion_format.setFontHeight(10)
red_portion_format.getFillFormat().setFillType(FillType.Solid)
red_portion_format.getFillFormat().getSolidFillColor().setColor(Color.WHITE)
# 添加蓝色系列。
series_cell = workbook.getCell(worksheet_index, 0, 2, "Blues")
blue_series = chart.getChartData().getSeries().add(series_cell, chart.getType())
for row_index, value in enumerate([0.70, 0.50, 0.20, 0.35], start=1):
data_cell = workbook.getCell(worksheet_index, row_index, 2, jpype.JDouble(value))
blue_series.getDataPoints().addDataPointForBarSeries(data_cell)
blue_series.getFormat().getFill().setFillType(FillType.Solid)
blue_series.getFormat().getFill().getSolidFillColor().setColor(Color.BLUE)
blue_label_format = blue_series.getLabels().getDefaultDataLabelFormat()
blue_label_format.setShowValue(True)
blue_label_format.setNumberFormatLinkedToSource(False)
blue_label_format.setNumberFormat("0.0%")
blue_portion_format = blue_label_format.getTextFormat().getPortionFormat()
blue_portion_format.setFontHeight(10)
blue_portion_format.getFillFormat().setFillType(FillType.Solid)
blue_portion_format.getFillFormat().getSolidFillColor().setColor(Color.WHITE)
presentation.save("SetDataLabelsPercentageSign_out.pptx", SaveFormat.Pptx)
finally:
presentation.dispose()
设置标签与坐标轴的距离
下面的 Python 代码演示在从坐标轴绘制的图表中如何设置标签与类别坐标轴的距离：
import jpype
import asposeslides
if not jpype.isJVMStarted():
jpype.startJVM()
from asposeslides.api import ChartType, Presentation, SaveFormat
presentation = Presentation()
try:
slide = presentation.getSlides().get_Item(0)
chart = slide.getShapes().addChart(ChartType.ClusteredColumn, 20, 20, 500, 300)
chart.getAxes().getHorizontalAxis().setLabelOffset(500)
presentation.save("output.pptx", SaveFormat.Pptx)
finally:
presentation.dispose()
调整标签位置
当创建不依赖任何坐标轴的图表（例如饼图）时，图表的数据标签可能会距离边缘过近。此时，需要调整数据标签的位置，以便清晰显示引线。
下面的 Python 代码演示如何在饼图上调整标签位置：
import jpype
import asposeslides
if not jpype.isJVMStarted():
jpype.startJVM()
from asposeslides.api import ChartType, LegendDataLabelPosition, Presentation, SaveFormat
presentation = Presentation()
try:
chart = presentation.getSlides().get_Item(0).getShapes().addChart(ChartType.Pie, 50, 50, 200, 200)
series = chart.getChartData().getSeries()
label = series.get_Item(0).getLabels().get_Item(0)
label.getDataLabelFormat().setShowValue(True)
label.getDataLabelFormat().setPosition(LegendDataLabelPosition.OutsideEnd)
label.setX(0.71)
label.setY(0.04)
presentation.save("pres.pptx", SaveFormat.Pptx)
finally:
presentation.dispose()
常见问题
如何防止在密集图表上数据标签重叠？
结合自动标签放置、引线以及减小字体大小；如有必要，可隐藏某些字段（例如类别），或仅对极端/关键点显示标签。
如何仅对零、负数或空值禁用标签？
在启用标签之前过滤数据点，并根据定义的规则关闭对值为 0、负数或缺失值的显示。
在导出为 PDF/图像时，如何确保标签样式一致？
显式设置字体（系列、大小），并确保渲染端可用该字体，以避免回退。