Python Rotation Matrix Error -


i getting not aligned shapes error in python , not sure how resolve it. goal take dot product between array , rotation matrix.

i calling 2 text file lists , converting them arrays. not converting 2 lists arrays , matrix form correctly? 

x=dataset[:,0]  y=dataset[:,1]  z_nodatum=dataset[:,2] stage=dataset[:,17] amp=dataset[:,5]  x=np.array(x) y=np.array(y)  z=-(z_nodatum-2919)  z=np.array(z)   = np.column_stack(([x],[y]))   theta = np.radians(20) c,s =np.cos(theta), np.sin(theta) r = np.matrix('{} {};{} {}' .format(c, -s, s, c))  b=a*r

also take b , convert x , y list plotting.

thanks help.

i'm guessing dataset array 2d array, , not that, it numpy array since can't index normal python arrays via [:(tuple)]

given that, appears these 5 lines

x=dataset[:,0]  y=dataset[:,1]  z_nodatum=dataset[:,2] stage=dataset[:,17] amp=dataset[:,5]

actually correspond specified columns in dataset. x, y, z_notatum, stage, , amp 1xn arrays.

given this, lines:

x=np.array(x) y=np.array(y)

do nothing, x , y numpy arrays. z=-(z_nodatum-2919) subtracts 2919 every element, negates result , returns resulting numpy array, if wanted. again, z=np.array(z) doesn't anything, had numpy array in first place.

this next line don't think want do. 

a = np.column_stack(([x],[y]))

what takes array of 1xn arrays x , y, , column stacks them, ends being [[x1, x2... xn, y1, y2...yn]]. wanted was:

a = np.column_stack((x,y))

which returns 2d numpy array of columns x , y [[x1,y1],[x2, y2]...[xn,yn]]. note if going x , y have done in beginning:

a = dataset[:,:2]

this have given x , y in first place if right next each other in dataset (takes 0 -> n-1 columns, n here 2)

your rotation matrix appears valid, note, should have created via:

theta = np.radians(20) cos_theta,sine_theta =np.cos(theta), np.sin(theta) r = np.matrix([[cos_theta, -sine_theta], [sine_theta, cos_theta]])

you use string format version when more convenient (ie reading text elsewhere) or have complicated structure necessitates it. not case here. 

b=a*r

in version have 1x1xn np array a, , 2x2 r. isn't going work.

with revised changes suggest, row x column, nx2 * 2x2 operation, valid since inner sizes match. rotated x , y out of b, can doing in beginning, b nx2 numpy array @ point (a*b = c, size of c a.rows x b.cols, outer size values):

x_rotated = b[:,0] y_rotated = b[:,1]

now should work. careful matrix multiplication in numpy though, make sure @ least 1 of values matrix, otherwise doing element wise multiplication (your r matrix). additionally order of operations may make 2 arrays in equation (ie array * array * matrix) perform element wise multiplication before matrix operation.


Comments

Post a Comment

Popular posts from this blog

inversion of control - Autofac named registration constructor injection -

does autofac support specifying registration name in components' constructors? example: ninject's namedattribute . you need use autofac.extras.attributed package on top achieve this so let's have 1 interface , 2 classes: public interface ihello { string sayhello(); } public class englishhello : ihello { public string sayhello() { return "hello"; } } public class frenchhello : ihello { public string sayhello() { return "bonjour"; } } then have consumer class, in want select instance injected: public class helloconsumer { private readonly ihello helloservice; public helloconsumer([withkey("en")] ihello helloservice) { if (helloservice == null) { throw new argumentnullexception("helloservice"); } this.helloservice = helloservice; } public string sayhello() { return this.helloservice.sayhello()...
Read more

verilog - Systemverilog dynamic casting issues -

i've code snippet following in testbench function void write_to_port( my_data_type_base data ); my_data_type_extended data_ext; if(!$cast(data_ext, data)); `uvm_error(get_type_name(), "failed cast"); `uvm_info(get_name(), $psprintf("data_ext :\n%s", data_ext.sprint()), uvm_medium) // write data_ext out port.... endfunction when run it, i'm getting uvm_error "failed cast." i'm not quire sure why $cast not returning 1. can see, i'm printing out extended class data item after casting uvm_info. can see it's being cast properly. if don't use $cast if condition, don't runtime error. isn't coding practice use if dynamic cast check if $cast returning 1 ? what might reason behind cast not returning 1 in above case? i think semicolon on line 'if' not belong? i think consumes if statement, , uvm_error executes regardless of how if evaluates: if(!$cast(data_ext, data)); <- no semico...
Read more

ios - Change Storyboard View using Seague -

i have following code checks connection server, , depending on want change views if no connection found. nsstring *connect = [nsstring stringwithcontentsofurl:[nsurl urlwithstring:@"http://myserver.com"] encoding:nsutf8stringencoding error:nil]; if (connect == null) { [self performseguewithidentifier:@"network_failure" sender:self]; } else { // other code here } my problem not change views. have added storyboard segue between 2 views identifier of network_failure . not have navigation controller or that, problem? thanks help! no not problem. first of all, in objectivec exists nil object oriented null . must use that. so: if(connect == nil) or better: if(!connect) so due fact nil not same of null , probably code does't enter in if scope . you have been able discover breakpoint. anyway: be sure set trigger segue (line) 2 view controller , , name network_failure (that not best name. should instead view1toview2 ) as, m...
Read more