how to plot winter rainfall data with trend line

1977-78 17,
1978-79 29,
1979-80 8,
1980-81 4,

Answer 1

[dpb]

y=[78:81].';r=[17 29 8 4].';
plot(y,r)
b=polyfit(y,r,1);
rhat=polyval(b,y);
hold on,plot(y,rhat,'r')
set(gca,'xtick',y)
xlim([y(1)-0.5 y(end)+0.5])
set(gca,'xticklabel',num2str([y-1 y]+1900,'%d-%d'))
xlabel('Winter Season of')
ylabel('Season rainfall (in)')

Salt to suit...

[skyhunt]

thank you for your replying me...u r script is not working..i attached my text file and correct this.

[dpb]

You'll have to write specific formatting to handle the dash in the first column of data when reading the file

[y1 y2 p]=textread('1.txt','%4d-%2d %f');

will return the full year in y1 and the two-digit second year in y2. You'll have to clean up the script to handle the labeling using full year values since the example didn't roll over the century I just used the 2-digit values. Can't do this with the full data set for obvious reasons.

doc textread % for details
doc textscan % alternative but returns cell arrays

etc., ...

[skyhunt]

[y1, y2, p]=textread('1.txt','%4d-%2d %f');
plot(y1,p)
b=polyfit(y1,p,1);
rhat=polyval(b,y1);
hold on,plot(y1,rhat,'r')
set(gca,'xtick',y1)
xlim([y1(1)-0.5 y1(end)+0.5])
set(gca,'xticklabel',num2str([y1-1 y1]+1900,'%d-%d'))
xlabel('Winter Season')
ylabel('Season rainfall (mm)')

x-axis some problem...please check it sir...

[dpb]

That's the comment I made earlier re: using 2-yr vis a vis 4-yr dates. "Exercise for the student..." :)

Decide what you want the labeling to be and then figure out the formatting to produce that. You could simply start with using y1 alone but it should be obvious that adding 1900 to an already-four-year value isn't going to be what you want.