Problem to plot GDP data coming from Wolfram Alpha

I'm working with economic data and realized that I could extract it directly from WolframAlpha using _Mathematica. So I did it. I extracted the GDP data of the country I'm studying.

nominal =
WolframAlpha[
"nominal gdp of brazil", {{"History:GDP:WorldDevelopmentData", 1},
"TimeSeriesData"},
PodStates -> {"History:GDP:WorldDevelopmentData__Linear scale"}];


So until now I'm ok. The trouble begins when I try to plot it using DateListPlot[nominal] because I just get an empty frame? I noticed that the GDP comes in US dollars and maybe some additional parameters are needed. I looked for it in the doc but couldn't find the solution. Thank's for the help.

Here goes a sample of what I got

{{{1960, 1, 1, 0, 0, 0.}, Quantity[1.51656*10^10, ("USDollars")/("Years")]},
{{1961, 1, 1, 0, 0, 0.}, Quantity[1.52369*10^10, ("USDollars")/("Years")]},
{{1962, 1, 1, 0, 0, 0.}, Quantity[1.99263*10^10, ("USDollars")/("Years")]},
{{1963, 1, 1, 0, 0, 0.}, Quantity[2.30215*10^10, ("USDollars")/("Years")]},
{{1964, 1, 1, 0, 0, 0.}, Quantity[2.12119*10^10, ("USDollars")/("Years")]},
{{1965, 1, 1, 0, 0, 0.}, Quantity[2.179*10^10, ("USDollars")/("Years")]},
{{1966, 1, 1, 0, 0, 0.}, Quantity[2.70627*10^10, ("USDollars")/("Years")]},
{{1967, 1, 1, 0, 0, 0.}, Quantity[3.05918*10^10, ("USDollars")/("Years")]},
{{1968, 1, 1, 0, 0, 0.}, Quantity[3.38759*10^10, ("USDollars")/("Years")]},
{{1969, 1, 1, 0, 0, 0.}, Quantity[3.74589*10^10, ("USDollars")/("Years")]}.........

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He goes a sample – DiegoOliveira Dec 29 '13 at 21:26
Nice to see another Brazilian user here! – Murta Dec 30 '13 at 10:13
Don't forget to upvote and accept useful answers. (You now have three questions and no accepted answers.) – Ajasja Dec 30 '13 at 10:25

I have no idea why DateListPlot does not work with Quantity. Perhaps it's a bug?

But the workaround is very easy: using pattern replacements we extract the numerical values.

DateListPlot[nominal /. Quantity[x_, _] :> x,
FrameLabel -> {"year", "\$ per year"}]


Browsing through the help, another option is QuantityMagnitude.

DateListPlot@QuantityMagnitude@nominal


Part is also very versatile. This should get rid of units:

ListPlot@nominal[[All, {1, 2}, 1]]


Note that this only works because we take just the first part of the date (the year).

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Thank you @Ajasja! Great! But I wonder that the real issue is : Weren't MM supposed to deal with the units automatically when plotting? Is there a way to do that? – DiegoOliveira Dec 29 '13 at 22:00
@DiegoOliveira No idea, I don't the new units that often. – Ajasja Dec 30 '13 at 9:09