## Libraries.Compute.Statistics.Calculations.Variance Documentation

This class calculates the variance of a particular DataFrameColumn. The variance calculated in this case is the sample variance. More information can be found about variance here: https://en.wikipedia.org/wiki/Variance

**Example Code**

```
use Libraries.Compute.Statistics.DataFrame
use Libraries.Compute.Statistics.Calculations.Variance
//Load a comma separated file
DataFrame frame
frame:Load("Data.csv")
Variance variance
//set the mean before using it. Alternatively, we can allow it to calculate for us.
//The result is received slightly faster if we set it.
variance:SetMean(17)
DataFrameColumn column = frame:GetColumn(0)
column:Calculate(variance)
number variance = variance:GetVariance()
```

*Inherits from: *Libraries.Language.Object, Libraries.Compute.Statistics.DataFrameColumnCalculation

## Summary

### Actions Summary Table

Actions | Description |
---|---|

Add(Libraries.Language.Object value) | If the calculation otherwise has no primitive type, it sends it to the column as a raw object. |

Add(Libraries.Language.Types.Integer value) | |

Add(Libraries.Language.Types.Boolean value) | If the calculation returns true from IsIterable, this is a Boolean object that was passed to the calculation. |

Add(Libraries.Language.Types.Number value) | |

Add(Libraries.Language.Types.Text value) | If the calculation returns true from IsIterable, this is a Text object that was passed to the calculation. |

Calculate(Libraries.Compute.Statistics.DataFrameColumn column) | This action can calculate the equation from a particular column. |

Compare(Libraries.Language.Object object) | This action compares two object hash codes and returns an integer. |

Empty() | This calculation can be used again if Empty is called after using it on a column. |

End(Libraries.Compute.Statistics.DataFrameColumn column) | This action is called at the end of a calculation. |

Equals(Libraries.Language.Object object) | This action determines if two objects are equal based on their hash code values. |

GetHashCode() | This action gets the hash code for an object. |

GetMean() | Returns the mean |

GetVariance() | Returns the sample variance. |

IsIterable() | If this action returns true, each element of the column will be sent to this calculation one by one. |

SetMean(number mean) | Sets the mean. |

Start(Libraries.Compute.Statistics.DataFrameColumn column) |

## Actions Documentation

### Add(Libraries.Language.Object value)

If the calculation otherwise has no primitive type, it sends it to the column as a raw object. Columns might use this if they have custom types.

#### Parameters

### Add(Libraries.Language.Types.Integer value)

#### Parameters

### Add(Libraries.Language.Types.Boolean value)

If the calculation returns true from IsIterable, this is a Boolean object that was passed to the calculation. This may be undefined, which indicates that the column did not contain a value at this position in the column.

#### Parameters

### Add(Libraries.Language.Types.Number value)

#### Parameters

### Add(Libraries.Language.Types.Text value)

If the calculation returns true from IsIterable, this is a Text object that was passed to the calculation. This may be undefined, which indicates that the column did not contain a value at this position in the column.

#### Parameters

### Calculate(Libraries.Compute.Statistics.DataFrameColumn column)

This action can calculate the equation from a particular column. By default this action will only be called if the Calculation is not Iterable. Because the Column class is not guaranteed to have any particular data type, individual Calculation classes may need to cast to a particular column or data type to perform their operations. If a calculation is Iterable, the column will pass all of its data, one by one, to the calculation instead.

#### Parameters

### Compare(Libraries.Language.Object object)

This action compares two object hash codes and returns an integer. The result is larger if this hash code is larger than the object passed as a parameter, smaller, or equal. In this case, -1 means smaller, 0 means equal, and 1 means larger. This action was changed in Quorum 7 to return an integer, instead of a CompareResult object, because the previous implementation was causing efficiency issues.

**Example Code**

```
Object o
Object t
integer result = o:Compare(t) //1 (larger), 0 (equal), or -1 (smaller)
```

#### Parameters

- Libraries.Language.Object: The object to compare to.

#### Return

integer: The Compare result, Smaller, Equal, or Larger.

### Empty()

This calculation can be used again if Empty is called after using it on a column.

### End(Libraries.Compute.Statistics.DataFrameColumn column)

This action is called at the end of a calculation.

#### Parameters

### Equals(Libraries.Language.Object object)

This action determines if two objects are equal based on their hash code values.

**Example Code**

```
use Libraries.Language.Object
use Libraries.Language.Types.Text
Object o
Text t
boolean result = o:Equals(t)
```

#### Parameters

- Libraries.Language.Object: The to be compared.

#### Return

boolean: True if the hash codes are equal and false if they are not equal.

### GetHashCode()

This action gets the hash code for an object.

**Example Code**

```
Object o
integer hash = o:GetHashCode()
```

#### Return

integer: The integer hash code of the object.

### GetMean()

Returns the mean

#### Return

number:

### GetVariance()

Returns the sample variance.

#### Return

number:

### IsIterable()

If this action returns true, each element of the column will be sent to this calculation one by one. If this is false, the column should ask this class to conduct the calculation all at once using the Calculate action.

#### Return

boolean:

### SetMean(number mean)

Sets the mean. The variance then uses this valus in its calculation.