Neo4j: Cypher - Rounding a float value to decimal places
About 6 months ago Jacqui Read created a github issue explaining how she wanted to round a float value to a number of decimal places but was unable to do so due to the http://docs.neo4j.org/chunked/stable/query-functions-mathematical.html#functions-round function not taking the appropriate parameter.
I found myself wanting to do the same thing last week where I initially had the following value:
RETURN toFloat("12.336666") AS valueI wanted to round that to 2 decimal places and Wes suggested multiplying the value before using ROUND and then dividing afterwards to achieve that.
For two decimal places we need to multiply and divide by 100:
WITH toFloat("12.336666") AS value
RETURN round(100 * value) / 100 AS value12.34Michael suggested abstracting the number of decimal places like so:
WITH 2 as precision
WITH toFloat("12.336666") AS value, 10^precision AS factor
RETURN round(factor * value)/factor AS valueIf we want to round to 4 decimal places we can easily change that:
WITH 4 as precision
WITH toFloat("12.336666") AS value, 10^precision AS factor
RETURN round(factor * value)/factor AS value12.3367The code is available as a graph gist too if you want to play around with it. And you may as well check out the other gists while you’re at it - enjoy!
About the author
I'm currently working on short form content at ClickHouse. I publish short 5 minute videos showing how to solve data problems on YouTube @LearnDataWithMark. I previously worked on graph analytics at Neo4j, where I also co-authored the O'Reilly Graph Algorithms Book with Amy Hodler.