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Version: Java (Groovy)

diff

The diff method returns the differences between two provided tables as a string. If the two tables are the same, an empty string is returned.

This method starts by comparing the table sizes and then the schema of the two tables, such as the number of columns, column names, column types, and column orders. If the schemas differ, the comparison stops, and the differences are returned. If the schemas are the same, the method compares the table data. The method compares the table data column by column (not row by row) and only records the first difference found in each column.

Note that inexact comparison of floating numbers may sometimes be desirable due to their inherent imprecision.

Syntax​

diff(actualResult, expectedResult, maxDiffLines)
diff(actualResult, expectedResult, maxDiffLines, itemsToSkip)

Parameters​

ParameterTypeDescription
actualResultTable

The table to compare.

expectedResultTable

The table to compare actualResult against.

maxDiffLineslong

The maximum number of differences to return.

itemsToSkipEnumSet<TableDiff.DiffItems>

EnumSet of checks not to perform.

  • ColumnsOrder: Columns that exist in both tables but in different orders are not treated as different.
  • DoubleFraction: Doubles and Floats are not treated as differences if they are within a factor of TableDiff.DOUBLE_EXACT_THRESHOLD or TableDiff.FLOAT_EXACT_THRESHOLD.
  • DoublesExaxt: Doubles and Floats are not treated as differences if they are within TableDiff.DOUBLE_EXACT_THRESHOLD or TableDiff.FLOAT_EXACT_THRESHOLD.

Returns​

The differences between actualResult and expectedResult as a string.

Examples​

In the following example, we use the diff method to compare two tables.

t1 = emptyTable(10).update("A = i", "B = i", "C = i")
t2 = emptyTable(10).update("A = i", "C = i % 2 == 0? i: i + 1", "C = i % 2 == 0? i + 1: i")

d = diff(t1, t2, 10).split("\n")

println d

Here, we have two identical tables, except that table t2 swaps columns B and C. We'll use the itemsToSkip parameter to ignore the column order.

import io.deephaven.engine.util.TableDiff.DiffItems

t1 = emptyTable(10).update("A = i", "B = i", "C = i")
t2 = emptyTable(10).update("A = i", "C = i", "B = i")


d = diff(t1, t2, 10, EnumSet.of(DiffItems.valueOf("ColumnsOrder")))
d2 = diff(t1, t2, 10)

println "d:" + d
println "d2: \n" + d2