Re: Map and functional constructs to replace iterative statements
- To: mathgroup at smc.vnet.net
- Subject: [mg96831] Re: Map and functional constructs to replace iterative statements
- From: dh <dh at metrohm.com>
- Date: Thu, 26 Feb 2009 07:51:12 -0500 (EST)
- References: <go31ba$f47$1@smc.vnet.net>
Hi Andreas, there are several solutions, but I think the most elegant is using vectors. E.g. assuming your data is in "d" 100 (Rest[d]-Most[d])/Most[d] hope this helps, Daniel Andreas wrote: > I have begun to replace Table, Do, While, or For, but in my thinking with Map, Inner, Outer and other functional programming constructs as I learn more about Mathematica. > > But, I'm stuck. I need to figure out how to use Map (or some related approach) when a function needs both a current value and a previous value in a time series, such as a percentage change function (or perhaps more generally stated, when I need to refer to previous values in a series or even previous calculations). But first a simple case: > > percentChange[currentValue_, previousValue_] := 100 * ( currentValue - previousValue) / previousValue > > I know how to apply this iteratively, but how can I do it with Map or some other functional construct? > > Say I have a list: timeSeries > > I thought to try something like this: > > Map[percentChange[?,?], timeSeries] > > but I don't know how what to put in for "?". > > Any help much appreciated. > > Thx. >