Pivot Data Type: Allow Sum/Count/Avarage

[qin-nz]

在 Excel 里， Pivot 表可以对值类型选择需要的操作，比如计数、求和、平均值

excelize.PivotTableOption{
        DataRange:       "Sheet1!$A$1:$E$31",
        PivotTableRange: "Sheet1!$G$2:$M$34",
        Rows:            []string{"Month", "Year"},
        Columns:         []string{"Type"},
        Data:            []string{"Sales"},
    }

是不是应该增加一个

   DataType:            []string{"Count"},

[xuri]

Hi, @qin-nz, thanks for your issue. I have added support for setting date field subtotal and names of the pivot table. Please try to upgrade the library with the master branch code.

[qin-nz]

@xuri Data is slice of string, so DataSubtotal should also be slice instead of string.
Excel allow different data use different fo subtotal type.

[xuri]

I have added a new structure PivotTableField to hold pivot table fields for better scalability, which caused API changes. In addition, two or more fields in Data are not supported currently.