# Turn the following values into percentage [closed]

I have the following data: {2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017} {5914, 6143, 6182, 18000, 18173, 18344, 18454, 18506, 18800, 19216} My data is already in Matrix form in Mathematica, is there a possibility to change the second raw into percentages? I want the first data: 5914 to be 100% and calculate how much did the data grow over the years based on the first year. So the last number should be: 324%. How could this be done automatically and for a huge set of data? Thank you!

• try this data = {{2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017}, {5914, 6143, 6182, 18000, 18173, 18344, 18454, 18506, 18800, 19216}}; secondData = data[[2]]; secondData = IntegerPart[N[#*100/First[secondData]]]& /@ secondData; data[[2]] = secondData; – Xminer Jan 4 '19 at 14:13
• Just divide your array with the first element? arr/First[arr]. You might want to go through some basic tutorials: wolfram.com/language/elementary-introduction/2nd-ed – Szabolcs Jan 4 '19 at 14:14

(I get to show this first...)

data = {{2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
2017}, {5914, 6143, 6182, 18000, 18173, 18344, 18454, 18506,
18800, 19216}};
{data[[1]], PercentForm[N[data[[2]]]/data[[2, 1]]]}


(...coming soon, in version 12)

• @RolfMertig The decimal point disparity was a design choice (at the insistence of the boss), to only put in a decimal when the value does not coerce to an integer. As for using N, we opted not to coerce exact values, other than integers, into percentages. So that was also a design choice. – Daniel Lichtblau Jan 4 '19 at 17:17
• Greetings to the boss: wrong design choice. It was always a pain to construct nicely aligned and consisent tables of real numbers. And what is even worse is that the documentation does not fit the behaviour of Mathematica anymore (at least in such type of details).I do remeber a time when the documentation coincided with the software (which was one reason I switched from Macsyma to Mathematica ...). – Rolf Mertig Jan 4 '19 at 21:59
• @RolfMertig I agree the alignment of numbers is not always easy. But I don't see what exact fractions have to do with formatting reals. On the topic of formatting reals, DecimalForm has seen some fixes.. – Daniel Lichtblau Jan 4 '19 at 23:04
• @ΑλέξανδροςΖεγγ Did you run the code I posted? – Daniel Lichtblau Jan 5 '19 at 16:04
• Is there already a timeline for v12.0? If you have any say in this, please just make sure there's a release candidate sent to testers before a 12.0 final suddenly appears ... – Szabolcs Jan 7 '19 at 11:38
data = {{2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017}, {5914, 6143,6182, 18000, 18173, 18344, 18454, 18506, 18800, 19216}}


There's no need to define additional variables,try

data[[2]] = 100 data[[2]]/data[[2, 1]]//Round[#,1]& (*//IntegerPart*)  ;
data
(*{{2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017},
{100,103, 104, 304, 307, 310, 312, 312, 317, 324}}*)

• In many applications, Round would be more appropriate than IntegerPart – Bob Hanlon Jan 4 '19 at 14:35
• @ Bob Hanlon Thanks, you're right (but it is a liitle bit slower ;-) ) – Ulrich Neumann Jan 4 '19 at 14:45
• @Ulrich If it is about speed, I'd prefer data[[2]] = Round[data[[2]] (100. /data[[2, 1]]), 1]. The converts to machine precision numbers and reduces the number of scalar-vector multiplications from 2 to 1. – Henrik Schumacher Jan 4 '19 at 15:01
• @ Henrik Thanks, my actual answer seems to be the power-version! – Ulrich Neumann Jan 4 '19 at 16:19

Similar to the above:

k = {{2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
2017} , {5914, 6143, 6182, 18000, 18173, 18344, 18454, 18506,
18800, 19216}}

k[[2]]=Flatten[Floor[100*Rest[k]/Flatten[Rest[k]][[1]]]]


Gives

{{2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017}, {100, 103, 104, 304, 307, 310, 312, 312, 317, 324}}