Question

那里有一个帖子，在一个非常具体的示例中描述了如何执行该操作：

https://community.powerbi.com/t5/Community-Blog/Linear-Interpolation-with-Power-BI/ba-p/341202

但是代码不是很可移植，因为它通过名称等来引用特定的列。

它也不会将代码打包为一个函数，因此您的超级查询将被大量额外的步骤和变量所困扰。

Answer 1

我编写了一个（相对）通用函数，用于在幂查询中插值（对于幂bi和m代码也很有用）。

它将一个表和两个列名作为输入。它根据最接近的x，y对输出具有内插的y缺失值的表-如通过数据的顺序（不是数值紧密度）所指示。如果您需要数值接近度，只需在传递给此函数之前按x（可能还有缓冲区）进行排序即可。

(Input as table, xColumn as text, yColumn as text) =>
//Interpolates missing yColumn values based on nearest existing xColumn, yColumn pairs
let
    Buffer = Table.Buffer(Input),
    //index for joining calculations and preserving original order
    #"Added Main Index" = Table.AddIndexColumn(Buffer, "InterpolateMainIndex", 0, 1),
    #"Two Columns and Index" = Table.RemoveColumns(#"Added Main Index", List.Select(Table.ColumnNames(#"Added Main Index"), each _ <> xColumn and _ <> yColumn and _ <> "InterpolateMainIndex")),
    #"Remove Blanks" = Table.SelectRows(#"Two Columns and Index", each Record.Field(_, yColumn) <> null and Record.Field(_, yColumn) <> ""),
    //index for refering to next non-blank record
    #"Added Sub Index" = Table.AddIndexColumn(#"Remove Blanks", "InterpolateSubIndex", 0, 1),
    //m = (y2 - y1) / (x2 - x1)
    m = Table.AddColumn(#"Added Sub Index",
                        "m",
                        each    (Number.From(Record.Field(_, yColumn))-Number.From(Record.Field(#"Added Sub Index"{[InterpolateSubIndex]+1}, yColumn))) / 
                                (Number.From(Record.Field(_, xColumn))-Number.From(Record.Field(#"Added Sub Index"{[InterpolateSubIndex]+1}, xColumn))),
                        type number),
    //b = y - m * x
    b = Table.AddColumn(m, "b", each Record.Field(_, yColumn) - [#"m"] * Number.From(Record.Field(_, xColumn)), type number),
    //rename  or remove columns to allow full join
    #"Renamed Columns" = Table.RenameColumns(b,{{"InterpolateMainIndex", "InterpolateMainIndexCopy"}}),
    xColumnmb = Table.RemoveColumns(#"Renamed Columns",{yColumn, xColumn, "InterpolateSubIndex"}),
    Join = Table.Join(#"Added Main Index", "InterpolateMainIndex", xColumnmb, "InterpolateMainIndexCopy", JoinKind.FullOuter),
    //enforce orignal sorting
    #"Sorted by Main Index" = Table.Sort(Join,{{"InterpolateMainIndex", Order.Ascending}}),
    #"Filled Down mb" = Table.FillDown(#"Sorted by Main Index",{"m", "b"}),
    //y = m * x + b
    Interpolate = Table.ReplaceValue(#"Filled Down mb",null,each ([m] * Number.From(Record.Field(_, xColumn)) + [b]),Replacer.ReplaceValue,{yColumn}),
    //clean up
    #"Remove Temporary Columns" = Table.RemoveColumns(Interpolate,{"m", "b", "InterpolateMainIndex", "InterpolateMainIndexCopy"}),
    #"Restore Types" = Value.ReplaceType(#"Remove Temporary Columns", Value.Type(Input))
in
    #"Restore Types"

如何在Power Query / Power BI中的列中插入缺失值？

1 个答案: