How to accurately display the calculation results of ECharts histogram floating point numbers?

ECharts Histogram Floating Point Precision Processing Techniques

When making bar charts with ECharts, you often encounter floating-point calculation accuracy problems. For example, results like "2897.3 5451.6 = 8348.900000000001" may appear after data calculation, affecting the aesthetics of the chart and the accuracy of the data. This article will explain how to accurately display the floating point calculation results in the ECharts bar chart.

The root cause of the problem and common misunderstandings

JavaScript's floating-point number operation is prone to cause accuracy losses. For example, the result of 2897.3 5451.6 is not the exact 8348.9. Although toFixed(n) method can format numbers, it cannot completely solve the accuracy problem. Improper use may lead to rounding errors. Although string simulation addition can avoid accuracy loss, it is complex in operation, and accuracy problems may occur again after converting back to numbers.

Solution: Control display accuracy

The solution is not to completely avoid the accuracy loss of floating-point calculations, but to control the display accuracy. It is recommended to keep the two decimal places after the decimal point, because the original data is usually not accurate enough to retain two decimal places and avoid excessive tails.

Before passing the calculation result to ECharts, use the toFixed(2) method to format the result into a string that retains two decimal places, and then use the string as a value in the ECharts series configuration. This not only ensures display accuracy, but also avoids the unappearance caused by displaying too long numbers.

Summarize

By controlling the display accuracy rather than trying to completely avoid the accuracy loss of floating-point number calculations, the problem of inaccurate floating-point number display in ECharts bar charts can be effectively solved, thereby improving the aesthetics of the chart and data accuracy. The toFixed(2) method is a simple and effective solution.

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