# pltoting a variable with dates on horizontial axis

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댓글: jonas 2018년 9월 13일
Hello,
I am importing a data from excel by clicking on excel file and than click import.
the first column in my data is date, that is year , quarter. I want to create a plot of the variables. that i have done but in the figure i want to have date on the horizontal axis. I am having trouble in having date on the horizontal axis.
and i want to shade some of the periods in my plot. like from 1948 to 1950.
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Stephen Cobeldick 2018년 9월 6일
I want to get the picture like this. Please let me now who i can do this. thanks

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### 답변(2개)

jonas 2018년 9월 5일
편집: jonas 2018년 9월 12일
Here is something you can work from. I used a trick with the stairs and area functions to make the shaded bars. It may have been a bit overkill to use datetime in this case, but I could not resist. You can skip the first part if you'd prefer to use fraction years.
t=data(:,1);
y=data(:,7)
% Convert to datetime
year = floor(t);
fyear = years(mod(t,1));
ts=datetime(year,1,1)+fyear;
%Plot data
figure
hold on
h=plot(ts,y)
% fancy some shading? write list of [start time1; end time1; start time2; end time2...] and so on:
t2=[11 1948;10 1949;7 1953;5 1954;6 1957;4 1958;4 1960;2 1961;12 1969;11 1970;11 1973;3 1975;1 1980;7 1980;7 1981;11 1982;7 1990;3 1991;3 2001;11 2001;12 2007;6 2009]
t2=datetime(0,t2(:,1),1)+years(t2(:,2))
y2=zeros(1,length(t2))
y2(1:2:end)=1e6
[xs,ys]=stairs(t2,y2)
ha=area(xs,ys,'facecolor',[0 0 0],'facealpha',.5,'edgecolor','none')
ylim([min(y) max(y)])
EDIT: Fixed an error found by Peter Perkins
##### 댓글 수: 11표시숨기기 이전 댓글 수: 10
Walter Roberson 2018년 9월 9일
t = mydata(:,1);
TIME = datenum([floor(t), round(mod(t,1)*30-2), 0*t+1]); %converts quarters from .1, .2, .3, .4 into appropriate months
y = mydata(:,2);
myrecessions = {'November 1948' , 'October 1949' ; 'July 1953', 'May 1954' ; 'August 1957', 'April 1958' ; 'April 1960' , 'February 1961' ; 'December 1969', 'November 1970' ; 'November 1973', 'March 1975' ; 'January 1980', 'July 1980' ; 'July 1981' , 'November 1982' ; 'July 1990' , 'March 1991' ; 'March 2001' , 'November 2001' ;
'December 2007' , 'June 2009' };
recessions_datenum = reshape(datenum(myrecessions(:), 'mmmm yyyy'),size(myrecessions));
figure(3)
plot(TIME,y)
recessionplot('recessions', recessions_datenum);
datetick('x','yyyy')
xlim(datenum([1948 1 1; 2011 12 31]))
Tested. But you should re-check which column of data you want to plot: before it was column 7 but you seem to have switched to column 2.

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Peter Perkins 2018년 9월 12일
If possible, use datetimes, not datenums. Jonas' answer seems good, except I think it isn't correct when dealing with the non-standard way that quarters are encoded as fractional years (as tenths!). I thik this would do it:
y = floor(t);
q = 10*years(mod(t,1)); % maybe even round this?
ts = datetime(y,1,1) + calquarters(q);
##### 댓글 수: 4표시숨기기 이전 댓글 수: 3
jonas 2018년 9월 13일

Thanks guys, I did not realize the fraction refered to quarter.

@Peter: Thanks a lot for the elaborate explanation. Did not know about calyear, which seems great for dealing with those annoying leap years!

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