Data Analysis Techniques in Geophysics Using MATLAB
CERI-7104/CIVL-8126 Data Analysis in Geophysics
i)
Intro to Matlab
Continued
Sample data processing and
selection exercise.
Make a sample random noise data set.
Find the mean, standard deviation
and select the data between
mean±standard deviation
(no loops or explicit if statements)
Make synthetic “data”
a=rand(100,1);
Plot histogram to see distribution
hist(a)
Now calculate the mean and standard deviation
m=mean(a)
s=std(a)
Plot data, line for mean, lines for mean±standard dev
plot(a,'.')
hold on
plot([0 100],[m m],'r')
plot([0 100],[m+s m+s],'g')
plot([0 100],[m-s m-s],'g')
indx=find(m-s<a&a<m+s)
;
plot(indx,a(indx),'*')
Now find all the points whose value is within one
standard deviation of the mean using the matlab find
function.
This returns the index numbers of the points
selected.
indx=find(m-s<a&a<m+s)
;
Now plot the selected points using the
index as the x value (data is plotted
against index) and the selected points.
plot(indx,a(indx),'*')
Data - blue dots.
Mean
–
red line
Mean±standard devaition
–
green lines
Selected data - red asterisks.
Redo with normal distribution around zero.
NO LOOPS
NO EXPLICIT IFs
Fully Matlab
vectorized.
Explore data processing, analysis, and visualization techniques in geophysics through MATLAB. Learn how to generate synthetic data, calculate mean and standard deviation, select data within a certain range, and plot the results effectively. Embrace the power of MATLAB for geophysical data exploration.
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Presentation Transcript
C E R I C E R I- -7 1 04/ C IV L 7 1 04/ C IV L - -8 1 2 6 D ata A nalysis in 8 1 2 6 D ata A nalysis in G eophysics G eophysics i) Intro to M atlab C ontinued
S ample data processing and selection exercise. M ake a sample random noise data set. F ind the mean, standard deviation and select the data between mean standard deviation (no loops or explicit if statements)
M ake synthetic data M ake synthetic data a=rand(100,1); P lot histogram to see distribution P lot histogram to see distribution hist(a)
N ow calculate the mean and standard deviation m=mean(a) s=std(a) P lot data, line for mean, lines for mean standard dev plot(a,'.') hold on plot([0 100],[m m],'r') plot([0 100],[m+s m+s],'g') plot([0 100],[m-s m-s],'g') indx=find(m-s<a&a<m+s); plot(indx,a(indx),'*')
N ow find all the points whose value is within one standard deviation of the mean using the matlab find function. T his returns the index numbers of the points selected. indx=find(m-s<a&a<m+s); Now plot the selected points using the index as the x value (data is plotted against index) and the selected points. plot(indx,a(indx),'*')
D ata - blue dots. M ean red line M ean standard devaition green lines S elected data - red asterisks.
R edo with normal distribution around zero. N O L O O P S N O E X P L IC IT IF s F ully M atlab vectorized.
