# how to select a row of data from a csv file that is imported into Matlab?

59 views (last 30 days)
Randy Chen on 15 Nov 2020
I need to read in a csv file and utilize a function that is built into matlab:
[a,ecc,incl,RAAN,argp,nu,truelon,arglat,lonper] = ijk2keplerian(r_ijk, v_ijk)
Here is what my csv file looks like:
how should I import this csv file into matlab and then make a set of row vectors r = [rx,ry,rz] and v = [vx,vy,vz] such that I can use the above function directly?
I also want to create a plot of all six elements returned by the ijk2keplerian(r_ijk, v_ijk) function vs time. How should I make a for loop such that the function ijk2keplerian(r_ijk, v_ijk) returns all 6 elements into lists so I can plot each of the six elements vs time (on the same plot with legend)?? Sai Veeramachaneni on 17 Nov 2020
Here are the few hints.
1. Use readtable function to read csv file into matlab as a table.
2. Get the required column of the table using tablevariablename.columnname
Example
filename='file.csv';
r=[table_data.rx(1),table_data.ry(1),table_data.rz(1)];
v=[table_data.vx(1),table_data.vy(1),table_data.vz(1)];
[a,ecc,incl,RAAN,argp,nu,truelon,arglat,lonper] = ijk2keplerian(r, v)
Sai Veeramachaneni on 18 Nov 2020
You can build row vector inside for loop and later use this vector to plot the graphs.
See below code for your reference.
column_a=[]
column_ecc=[]
column_incl=[]
for i = 1:length(table_data.rx)
r=[table_data.rx(i),table_data.ry(i),table_data.rz(i)];
v=[table_data.vx(i),table_data.vy(i),table_data.vz(i)];
[a,ecc,incl,RAAN,argp,nu,truelon,arglat,lonper] = ijk2keplerian(r, v);
column_a=[column_a a]; %Storing value a inside row vector
column_ecc=[column_ecc ecc];
column_incl=[column_incl incl];
end
plot(column_a,t)%t is the time
plot(column_ecc,t);
plot(column_incl,t);