VARIF Function

Generates the variance of values by group in a column that meet a specific condition.

NOTE: When added to a transform, this function is applied to the current sample. If you change your sample or run the job, the computed values for this function are updated. Transforms that change the number of rows in subsequent recipe steps do not affect the values computed for this step.

For more information on how the platform calculates variance, see VAR Function.

Basic Usage

pivot value: VARIF(testScores, ((testScores > 0) && (testScores < 90)) group:studentId limit:1

Output: Generates a two-column table containing the unique values for studentId and the variance of the testScores column for that studentId value when the testScores value is between 0 and 90. The limit parameter defines the maximum number of output columns.

Syntax

pivot value:VARIF(col_ref, test_expression) [group:group_col_ref] [limit:limit_count]

ArgumentRequired?Data TypeDescription
col_refYstringReference to the column you wish to evaluate.
test_expressionYstringExpression that is evaluated. Must resolve to true or false

For more information on syntax standards, see Language Documentation Syntax Notes.

For more information on the group and limit parameters, see Pivot Transform.

col_ref

Name of the column whose values you wish to use in the calculation. Column must be a numeric (Integer or Decimal) type.

Usage Notes:

Required?Data TypeExample Value
YesString that corresponds to the name of the columnmyValues

test_expression

This parameter contains the expression to evaluate. This expression must resolve to a Boolean (true or false) value.

Usage Notes:

Required?Data TypeExample Value
YesString expression that evaluates to true or false(LastName == 'Mouse' && FirstName == 'Mickey')

Examples

Example - Conditional Calculation Functions

This example illustrates how you can use the following conditional calculation functions to analyze weather data:

  • AVERAGEIF - Average of a set of values by group that meet a specified condition. See AVERAGEIF Function.
  • MINIF - Minimum of a set of values by group that meet a specified condition. See MINIF Function.
  • MAXIF - Maximum of a set of values by group that meet a specified condition. See MAXIF Function.
  • VARIF - Variance of a set of values by group that meet a specified condition. See VARIF Function.
  • STDEVIF - Standard deviation of a set of values by group that meet a specified condition. See STDEVIF Function.

Source:

Here is some example weather data:

datecityrain_cmtemp_Cwind_mph
1/23/17Valleyville0.0012.86.7
1/23/17Center Town0.319.45.3
1/23/17Magic Mountain0.000.07.3
1/24/17Valleyville0.2517.23.3
1/24/17Center Town0.541.17.6
1/24/17Magic Mountain0.325.08.8
1/25/17Valleyville0.023.36.8
1/25/17Center Town0.833.35.1
1/25/17Magic Mountain0.59-1.76.4
1/26/17Valleyville1.0815.04.2
1/26/17Center Town0.966.17.6
1/26/17Magic Mountain0.77-3.93.0
1/27/17Valleyville1.007.22.8
1/27/17Center Town1.3220.00.2
1/27/17Magic Mountain0.775.65.2
1/28/17Valleyville0.12-6.15.1
1/28/17Center Town0.145.04.9
1/28/17Magic Mountain1.501.10.4
1/29/17Valleyville0.3613.37.3
1/29/17Center Town0.756.19.0
1/29/17Magic Mountain0.603.36.0


Transform:

The following computes average temperature for rainy days by city:

derive type:single value:AVERAGEIF(temp_C, rain_cm > 0) group:city as:'avgTempWRain'

The following computes maximum wind for sub-zero days by city:

derive type:single value:MAXIF(wind_mph,temp_C < 0) group:city as:'maxWindSubZero'

This step calculates the minimum temp when the wind is less than 5 mph by city:

derive type:single value:MINIF(temp_C,wind_mph<5) group:city as:'minTempWind5'

This step computes the variance in temperature for rainy days by city:

derive type:single value:VARIF(temp_C,rain_cm >0) group:city as:'varTempWRain'

The following computes the standard deviation in rainfall for Center Town:

derive type:single value:STDEVIF(rain_cm,city=='Center Town') as:'stDevRainCenterTown'

You can use the following transforms to format the generated output. Note the $col placeholder value for the multi-column transforms:

set col:stDevRainCenterTown,maxWindSubZero value:numformat($col,'##.##')

Since the following rely on data that has only one significant digit, you should format them differently:

set col:varTempWRain,avgTempWRain,minTempWind5 value:numformat($col,'##.#')

Results:

Here is some example weather data:

datecityrain_cmtemp_Cwind_mphavgTempWRainmaxWindSubZerominTempWind5varTempWRainstDevRainCenterTown
1/23/17Valleyville0.0012.86.78.35.17.263.80.37
1/23/17Center Town0.319.45.37.3 532.60.37
1/23/17Magic Mountain0.000.07.31.66.43-3.9120.37
1/24/17Valleyville0.2517.23.38.35.17.263.80.37
1/24/17Center Town0.541.17.67.3 532.60.37
1/24/17Magic Mountain0.325.08.81.66.43-3.9120.37
1/25/17Valleyville0.023.36.88.35.17.263.80.37
1/25/17Center Town0.833.35.17.3 532.60.37
1/25/17Magic Mountain0.59-1.76.41.66.43-3.9120.37
1/26/17Valleyville1.0815.04.28.35.17.263.80.37
1/26/17Center Town0.966.17.67.3 532.60.37
1/26/17Magic Mountain0.77-3.93.01.66.43-3.9120.37
1/27/17Valleyville1.007.22.88.35.17.263.80.37
1/27/17Center Town1.3220.00.27.3 532.60.37
1/27/17Magic Mountain0.775.65.21.66.43-3.9120.37
1/28/17Valleyville0.12-6.15.18.35.17.263.80.37
1/28/17Center Town0.145.04.97.3 532.60.37
1/28/17Magic Mountain1.501.10.41.66.43-3.9120.37
1/29/17Valleyville0.3613.37.38.35.17.263.80.37
1/29/17Center Town0.756.19.07.3 532.60.37
1/29/17Magic Mountain0.603.36.01.66.43-3.9120.37

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