# Wolfram 语言™

## 数量数组

QuantityArray 允许有效储存和 Quantity 对象的数组操作，这对有物理单位的数据分析而言是理想条件. 在全系统继续数量集合，一些函数现在可理解并返回 QuantityArray 对象.

In[1]:=
`RandomVariate[ParetoDistribution[Quantity[500., "USDollars"], 4], 300]`
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QuantityArray 对象等价于 Quantity 元素的正态数组.

In[2]:=
```RandomVariate[ParetoDistribution[Quantity[500., "USDollars"], 4], 300]; Normal[Take[%, 10]]```
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In[3]:=
`GeoElevationData[Entity["Country", "UnitedStates"]]`
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In[4]:=
```GeomagneticModelData[ Entity["GeographicRegion", "Antarctica"], "Magnitude"]```
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In[5]:=
```GeoElevationData[ Entity["Country", "UnitedStates"], "Undulation", GeoPosition]```
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In[6]:=
```GeoElevationData[ Entity["Country", "UnitedStates"], "Undulation", GeoPosition]; LatitudeLongitude[%]```
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In[7]:=
```data = GeogravityModelData[Entity["Country", "China"], "DownComponent"]```
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In[8]:=
```contourplot = ListContourPlot[data - Quantity[1, "StandardAccelerationOfGravity"], Frame -> False, PlotRangePadding -> 0, ColorFunction -> "SolarColors"]```
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In[9]:=
```Legended[GeoGraphics[{GeoStyling[{"GeoImage", contourplot}, Opacity[0.8]], Polygon[Entity["Country", "China"]]}, ImageSize -> 500, GeoRange -> Quantity[2200, "Kilometers"], GeoZoomLevel -> 5], BarLegend[{"SolarColors", MinMax@Flatten[QuantityMagnitude@data]}]]```
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