使用 Python 在演示文稿中管理图表数据标签
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介绍
数据标签显示图表系列和单个数据点的信息，帮助读者识别数值并理解图表。本文介绍如何格式化数值、显示百分比、读取标签文本、调整类目轴标签间距以及定位饼图标签。
在图表数据标签中设置数据精度
使用number_format_of_values来格式化系列值。此示例创建一个带默认数据的折线图，显示其数据表，并为第一系列启用数值标签。格式#,##0.00显示千位分隔符和两位小数，而不更改底层数值。
import aspose.slides as slides
import aspose.slides.charts as charts
with slides.Presentation() as presentation:
slide = presentation.slides[0]
chart = slide.shapes.add_chart(charts.ChartType.LINE, 50, 50, 450, 300)
chart.has_data_table = True
series = chart.chart_data.series[0]
series.number_format_of_values = "#,##0.00"
series.labels.default_data_label_format.show_value = True
presentation.save("PrecisionOfDatalabels_out.pptx", slides.export.SaveFormat.PPTX)
显示百分比为标签
对于堆积柱形图，计算每个值相对于其类别总计的百分比，并将文本分配给text_frame_for_overriding。此示例使用默认图表数据，并以8磅字体显示两位小数的百分比。总计为零的类别将被跳过，以避免除以零。如果图表数据更改，需要重新计算自定义标签文本。
import aspose.slides as slides
import aspose.slides.charts as charts
with slides.Presentation() as presentation:
slide = presentation.slides[0]
chart = slide.shapes.add_chart(charts.ChartType.STACKED_COLUMN, 20, 20, 400, 400)
category_totals = [0.0] * len(chart.chart_data.categories)
for k in range(len(chart.chart_data.categories)):
for series in chart.chart_data.series:
point_value = float(series.data_points[k].value.data)
category_totals[k] += point_value
for series in chart.chart_data.series:
series.labels.default_data_label_format.show_legend_key = False
for j in range(len(series.data_points)):
label = series.data_points[j].label
if category_totals[j] == 0:
continue
point_value = float(series.data_points[j].value.data)
data_point_percent = point_value / category_totals[j] * 100
portion = slides.Portion()
portion.text = f"{data_point_percent:.2f} %"
portion.portion_format.font_height = 8
label.text_frame_for_overriding.text = ""
paragraph = label.text_frame_for_overriding.paragraphs[0]
paragraph.portions.add(portion)
label.data_label_format.show_value = True
label.data_label_format.show_series_name = False
label.data_label_format.show_percentage = False
label.data_label_format.show_legend_key = False
label.data_label_format.show_category_name = False
label.data_label_format.show_bubble_size = False
presentation.save("DisplayPercentageAsLabels_out.pptx", slides.export.SaveFormat.PPTX)
使用图表数据标签设置百分号
当数值以分数形式存储时，使用number_format显示百分比。将is_number_format_linked_to_source设置为False，以使标签格式独立于源单元格。
此示例创建一个100%堆积柱形图，包含红色和蓝色系列，跨越四个类别。每对数值相加为1。标签格式0.0%将0.30显示为30.0%，而垂直轴使用两位小数。两个系列的标签文本均为白色、10磅。
import aspose.slides as slides
import aspose.slides.charts as charts
import aspose.pydrawing as drawing
with slides.Presentation() as presentation:
slide = presentation.slides[0]
chart = slide.shapes.add_chart(charts.ChartType.PERCENTS_STACKED_COLUMN, 20, 20, 500, 400)
chart.axes.vertical_axis.is_number_format_linked_to_source = False
chart.axes.vertical_axis.number_format = "0.00%"
chart.chart_data.series.clear()
chart.chart_data.categories.clear()
workbook = chart.chart_data.chart_data_workbook
worksheet_index = 0
for i in range(4):
category_cell = workbook.get_cell(worksheet_index, i + 1, 0, f"Category {i + 1}")
chart.chart_data.categories.add(category_cell)
series_names = ["Reds", "Blues"]
series_colors = [drawing.Color.red, drawing.Color.blue]
values = [[0.30, 0.50, 0.80, 0.65], [0.70, 0.50, 0.20, 0.35]]
for i in range(len(series_names)):
series_cell = workbook.get_cell(worksheet_index, 0, i + 1, series_names[i])
series = chart.chart_data.series.add(series_cell, chart.type)
for j in range(4):
value_cell = workbook.get_cell(worksheet_index, j + 1, i + 1, values[i][j])
series.data_points.add_data_point_for_bar_series(value_cell)
series.format.fill.fill_type = slides.FillType.SOLID
series.format.fill.solid_fill_color.color = series_colors[i]
label_format = series.labels.default_data_label_format
label_format.show_value = True
label_format.is_number_format_linked_to_source = False
label_format.number_format = "0.0%"
label_format.text_format.portion_format.font_height = 10
label_format.text_format.portion_format.fill_format.fill_type = slides.FillType.SOLID
label_format.text_format.portion_format.fill_format.solid_fill_color.color = drawing.Color.white
presentation.save("SetDataLabelsPercentageSign_out.pptx", slides.export.SaveFormat.PPTX)
读取数据标签的实际文本
使用get_actual_label_text检索数据标签设置产生的文本。这在提取报告标签、搜索演示内容或验证生成的图表时非常有用。在下面的示例中，默认data label format将每个类别名称、系列名称和数值组合在一起。一个点将其数值格式化为百分比，另一个使用来自text_frame_for_overriding的自定义文本。
import aspose.slides as slides
import aspose.slides.charts as charts
with slides.Presentation() as presentation:
slide = presentation.slides[0]
chart = slide.shapes.add_chart(charts.ChartType.CLUSTERED_COLUMN, 20, 20, 500, 300)
chart.chart_data.series.clear()
chart.chart_data.categories.clear()
workbook = chart.chart_data.chart_data_workbook
for i, category_name in enumerate(["Q1", "Q2"]):
category_cell = workbook.get_cell(0, i + 1, 0, category_name)
chart.chart_data.categories.add(category_cell)
north_cell = workbook.get_cell(0, 0, 1, "North")
north = chart.chart_data.series.add(north_cell, chart.type)
for i, value in enumerate([0.25, 0.75]):
value_cell = workbook.get_cell(0, i + 1, 1, value)
north.data_points.add_data_point_for_bar_series(value_cell)
south_cell = workbook.get_cell(0, 0, 2, "South")
south = chart.chart_data.series.add(south_cell, chart.type)
for i, value in enumerate([0.40, 0.60]):
value_cell = workbook.get_cell(0, i + 1, 2, value)
south.data_points.add_data_point_for_bar_series(value_cell)
for series in chart.chart_data.series:
label_format = series.labels.default_data_label_format
label_format.show_category_name = True
label_format.show_series_name = True
label_format.show_value = True
north.labels[1].data_label_format.is_number_format_linked_to_source = False
north.labels[1].data_label_format.number_format = "0%"
south.labels[0].text_frame_for_overriding.text = "Reviewed"
for series in chart.chart_data.series:
for point in series.data_points:
label = point.label
if not label.is_visible:
continue
label_text = label.get_actual_label_text()
print(f"Value: {point.value.data}; label: {label_text}")
数据点中存储的数值仍为0.75，即使其标签显示75%并附带类别和系列名称。自定义文本会替换生成的标签文本。get_actual_label_text在两种情况下都会返回相应的标签字符串。正如上文所示，当只想提取可见标签时，需要单独检查is_visible。
设置标签相对于坐标轴的距离
使用label_offset控制类目轴标签与坐标轴之间的距离。该值是轴标签最大字体大小的百分比。此示例创建一个簇状柱形图，并将水平轴标签偏移设置为500。此设置影响类目轴标签，而不是附加到单个数据点的标签。
import aspose.slides as slides
import aspose.slides.charts as charts
with slides.Presentation() as presentation:
slide = presentation.slides[0]
chart = slide.shapes.add_chart(charts.ChartType.CLUSTERED_COLUMN, 20, 20, 500, 300)
chart.axes.horizontal_axis.label_offset = 500
presentation.save("SetCategoryAxisLabelDistance_out.pptx", slides.export.SaveFormat.PPTX)
调整标签位置
在饼图中，调整数据标签位置以改善间距并为引线留出空间。
此示例显示第一个数据点的数值，将其标签置于切片外部，并调整其x和y偏移。这些偏移分别相对于图表的宽度和高度。
import aspose.slides as slides
import aspose.slides.charts as charts
with slides.Presentation() as presentation:
slide = presentation.slides[0]
chart = slide.shapes.add_chart(charts.ChartType.PIE, 50, 50, 200, 200)
series = chart.chart_data.series
label = series[0].labels[0]
label.data_label_format.show_value = True
label.data_label_format.position = charts.LegendDataLabelPosition.OUTSIDE_END
label.x = 0.71
label.y = 0.04
presentation.save("presentation.pptx", slides.export.SaveFormat.PPTX)
常见问题
如何防止在密集图表上数据标签重叠？
结合自动标签布局、引线和减小字体大小；必要时隐藏某些字段（例如类别），或仅对极值或关键点显示标签。
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？
明确设置字体族和字号，并确认渲染环境中存在该字体，以避免回退。