Table Calculations 入門

Tableau 計算

Agata Bak-Geerinck

Senior Data Analyst, Telenet

什麼是 Table Calculations？

Table Calculation 是只根據目前畫布上可見內容，對視覺化數值做的轉換。

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忽略被篩選掉或不在畫布上的量測或維度

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在 Tableau 的本機資料上計算

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檢視中的虛擬資料表，與底層資料來源相對

Table Calculations 與資料來源

底層資料集：

An example of the dataset, with orders, products, sellers, region and profit

視覺化：

An example of a bar chart, with products in rows and summed profit in columns

虛擬資料表：

An example of a virtual table, with product and sum of profit.

Table Calculations 範例

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Running（累計）：

Two bar charts, left one presenting sum of profit per quarter, right one presenting running total of this summed profit, per quarter

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Percentage of total：

Two bar charts, left one presenting sum of profit per quarter, right one presenting percentage of quarterly profit in a year

Table Calculations 範例

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Difference from：

Two bar charts, left one presenting sum of profit per quarter, right one presenting a difference of the sum of profit from the preceding quarter

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Ranking：

Two bar charts, left one presenting sum of profit per quarter, right one presenting ranking of quarters based on the sum of profit

Tableau 的 Quick Table Calculations

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Tableau UI screenshot, presenting how to access Quick Table Calculations

¹ Tableau 以內建的 Quick Table Calculations 讓常見計算更容易。

多維度：位址與分割

每年各產品利潤

A table presenting profit for two products, per month and year

分割（Partitions）：

決定分組方式的維度＝作用範圍
- 例如 1）依年份、月份
- 例如 2）依產品、年份

其餘維度＝位址欄位（addressing fields）：

決定計算的方向：
- 例如 2）月份是位址欄位：由新到舊排序會改變計算結果

Table Calculations 的公式

Running 函式：

例如 RUNNING_SUM()、RUNNING_AVG()…

Example of a running sum formula

Window 函式：

例如 WINDOW_SUM()、WINDOW_AVG()…

Example of a window sum formula

每年各產品利潤

Table of profit per product, month and year, with a running sum calculation

每年各產品利潤

Table of profit per product, month and year, with a window sum calculation

Tableau 的 Table Calculations 助理

A visual of Tableau's Table Calculations assistant

資料集：英國服飾業

A visual with a silhouette of the United Kingdom and examples of textile products sold, e.g. a sweater

一起來練習吧！

Tableau 計算