EXAMPLE

Excerpt
This example illustrates you to apply percentile functions.

Functions:

D generate list excerpts

pages	MEDIAN Function,PERCENTILE Function,QUARTILE Function,APPROXIMATEMEDIAN Function,APPROXIMATEPERCENTILE Function,APPROXIMATEQUARTILE Function

Source:

The following table lists each student's height in inches:

Transformation:

Use the following transformations to calculate the median height in inches, a specified percentile and the first quartile.

The first function uses a precise algorithm which can be slow to execute across large datasets.
The second function uses an appropriate approximation algorithm, which is much faster to execute across large datasets.
- These approximate functions can use an error boundary parameter, which is set to 0.4 (0.4%) across all functions.

Median: This transformation calculates the median value, which corresponds to the 50th percentile.

D trans

RawWrangle	true
p03Value	'medianIn'
Type	step
WrangleText	derive type: single value: median(heightIn) as: 'medianIn'
p01Name	Formula type
p01Value	Single row formula
p02Name	Formula
p02Value	median(heightIn)
p03Name	New column name
SearchTerm	New formula

D trans

RawWrangle	true
p03Value	'approxMedianIn'
Type	step
WrangleText	derive type: single value: approxmedian(heightIn, 0.4) as: 'approxMedianIn'
p01Name	Formula type
p01Value	Single row formula
p02Name	Formula
p02Value	approximatemedian(heightIn, 0.4)
p03Name	New column name
SearchTerm	New formula

Percentile: This transformation calculates the 68th percentile.

D trans

RawWrangle	true
p03Value	'percentile68In'
Type	step
WrangleText	derive type: single value: percentile(heightIn, 68, linear) as: 'percentile68In'
p01Name	Formula type
p01Value	Single row formula
p02Name	Formula
p02Value	percentile(heightIn, 68, linear)
p03Name	New column name
SearchTerm	New formula

D trans

RawWrangle	true
p03Value	'approxPercentile68In'
Type	step
WrangleText	derive type: single value: approximatepercentile(heightIn, 68, 0.4) as: 'approxpercentile68In'
p01Name	Formula type
p01Value	Single row formula
p02Name	Formula
p02Value	approximatepercentile(heightIn, 68, 0.4)
p03Name	New column name
SearchTerm	New formula

Quartile: This transformation calculates the first quartile, which corresponds to the 25th percentile.

D trans

RawWrangle	true
p03Value	'percentile25In'
Type	step
WrangleText	derive type: single value: quartile(heightIn, 1, linear) as: 'percentile25In'
p01Name	Formula type
p01Value	Single row formula
p02Name	Formula
p02Value	quartile(heightIn, 1, linear)
p03Name	New column name
SearchTerm	New formula

D trans

RawWrangle	true
p03Value	'approxPercentile25In'
Type	step
WrangleText	derive type: single value: approximatequartile(heightIn, 1, 0.4) as: 'approxPercentile25In'
p01Name	Formula type
p01Value	Single row formula
p02Name	Formula
p02Value	approximatequartile(heightIn, 1, 0.4)
p03Name	New column name
SearchTerm	New formula

Results:

studentId	heightIn	approxPercentile25In	percentile25In	approxPercentile68In	percentile68In	approxMedianIn	medianIn
1	64	64	64	67.1	66.92	66	66
2	65	64	64	67.1	66.92	66	66
3	63	64	64	67.1	66.92	66	66
4	64	64	64	67.1	66.92	66	66
5	62	64	64	67.1	66.92	66	66
6	66	64	64	67.1	66.92	66	66
7	66	64	64	67.1	66.92	66	66
8	65	64	64	67.1	66.92	66	66
9	69	64	64	67.1	66.92	66	66
10	66	64	64	67.1	66.92	66	66
11	73	64	64	67.1	66.92	66	66
12	69	64	64	67.1	66.92	66	66
13	69	64	64	67.1	66.92	66	66
14	61	64	64	67.1	66.92	66	66
15	64	64	64	67.1	66.92	66	66
16	61	64	64	67.1	66.92	66	66
17	71	64	64	67.1	66.92	66	66
18	67	64	64	67.1	66.92	66	66
19	73	64	64	67.1	66.92	66	66
20	66	64	64	67.1	66.92	66	66

D s also

label	example_percentile_functions

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