9.5.10 Arrays

Functions which perform aggregating operations on array-valued cells. The functions in this class such as mean, sum, maximum etc can only be used on values which are already arrays. In most cases that means on values in table columns which are declared as array-valued. FITS and VOTable tables can have columns which contain array values, but other formats such as CSV cannot.

There is also a set of functions named array with various numbers of arguments, which let you assemble an array value from a list of scalar numbers. This can be used for instance to get the mean of a set of three magnitudes by using an expression like "mean(array(jmag, hmag, kmag))".

sum( array )

Returns the sum of all the non-blank elements in the array. If array is not a numeric array, null is returned.

• array (Object): array of numbers
• return value (floating point): sum of all the numeric values in array

mean( array )

Returns the mean of all the non-blank elements in the array. If array is not a numeric array, null is returned.

• array (Object): array of numbers
• return value (floating point): mean of all the numeric values in array

variance( array )

Returns the population variance of all the non-blank elements in the array. If array is not a numeric array, null is returned.

• array (Object): array of numbers
• return value (floating point): variance of the numeric values in array

stdev( array )

Returns the population standard deviation of all the non-blank elements in the array. If array is not a numeric array, null is returned.

• array (Object): array of numbers
• return value (floating point): standard deviation of the numeric values in array

minimum( array )

Returns the smallest of the non-blank elements in the array. If array is not a numeric array, null is returned.

• array (Object): array of numbers
• return value (floating point): minimum of the numeric values in array

maximum( array )

Returns the largest of the non-blank elements in the array. If array is not a numeric array, null is returned.

• array (Object): array of numbers
• return value (floating point): maximum of the numeric values in array

median( array )

Returns the median of the non-blank elements in the array. If array is not a numeric array, null is returned.

• array (Object): array of numbers
• return value (floating point): median of the numeric values in array

quantile( array, quant )

Returns a quantile value of the non-blank elements in the array. Which quantile is determined by the quant value; values of 0, 0.5 and 1 give the minimum, median and maximum respectively. A value of 0.99 would give the 99th percentile.

• array (Object): array of numbers
• quant (floating point): number in the range 0-1 deterining which quantile to calculate
• return value (floating point): quantile corresponding to quant

size( array )

Returns the number of elements in the array. If array is not an array, zero is returned.

• array (Object): array
• return value (integer): size of array

count( array )

Returns the number of non-blank elements in the array. If array is not an array, zero is returned.

• array (Object): array (may or may not be numeric)
• return value (integer): number of non-blank elements in array

join( array, joiner )

Returns a string composed of concatenating all the elements of an array, separated by a joiner string. If array is not an array, null is returned.

• array (Object): array of numbers or strings
• joiner (String): text string to interpose between adjacent elements
• return value (String): string composed of array elements separated by joiner strings

array( x1 )

Returns a numeric array built from a given element.

• x1 (floating point): array element 1
• return value (array of floating point): 1-element array

array( x1, x2 )

Returns a numeric array built from given elements.

• x1 (floating point): array element 1
• x2 (floating point): array element 2
• return value (array of floating point): 2-element array

array( x1, x2, x3 )

Returns a numeric array built from given elements.

• x1 (floating point): array element 1
• x2 (floating point): array element 2
• x3 (floating point): array element 3
• return value (array of floating point): 3-element array

array( x1, x2, x3, x4 )

Returns a numeric array built from given elements.

• x1 (floating point): array element 1
• x2 (floating point): array element 2
• x3 (floating point): array element 3
• x4 (floating point): array element 4
• return value (array of floating point): 4-element array

array( x1, x2, x3, x4, x5 )

Returns a numeric array built from given elements.

• x1 (floating point): array element 1
• x2 (floating point): array element 2
• x3 (floating point): array element 3
• x4 (floating point): array element 4
• x5 (floating point): array element 5
• return value (array of floating point): 5-element array

array( x1, x2, x3, x4, x5, x6 )

Returns a numeric array built from given elements.

• x1 (floating point): array element 1
• x2 (floating point): array element 2
• x3 (floating point): array element 3
• x4 (floating point): array element 4
• x5 (floating point): array element 5
• x6 (floating point): array element 6
• return value (array of floating point): 6-element array

array( x1, x2, x3, x4, x5, x6, x7 )

Returns a numeric array built from given elements.

• x1 (floating point): array element 1
• x2 (floating point): array element 2
• x3 (floating point): array element 3
• x4 (floating point): array element 4
• x5 (floating point): array element 5
• x6 (floating point): array element 6
• x7 (floating point): array element 7
• return value (array of floating point): 7-element array

array( x1, x2, x3, x4, x5, x6, x7, x8 )

Returns a numeric array built from given elements.

• x1 (floating point): array element 1
• x2 (floating point): array element 2
• x3 (floating point): array element 3
• x4 (floating point): array element 4
• x5 (floating point): array element 5
• x6 (floating point): array element 6
• x7 (floating point): array element 7
• x8 (floating point): array element 8
• return value (array of floating point): 8-element array