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# Using RxODE data frames

RxODE supports returning a solved object that is a modified data-frame. This is done by the `predict()`, `solve()`, or `rxSolve()` methods.

``````library(RxODE)
## Setup example model
mod1 <-RxODE({
C2 = centr/V2;
C3 = peri/V3;
d/dt(depot) =-KA*depot;
d/dt(centr) = KA*depot - CL*C2 - Q*C2 + Q*C3;
d/dt(peri)  =                    Q*C2 - Q*C3;
d/dt(eff)  = Kin - Kout*(1-C2/(EC50+C2))*eff;
});

## Seup parameters and initial conditions

theta <-
c(KA=2.94E-01, CL=1.86E+01, V2=4.02E+01, # central
Q=1.05E+01,  V3=2.97E+02,              # peripheral
Kin=1, Kout=1, EC50=200)               # effects

inits <- c(eff=1);

## Setup dosing event information
ev <- eventTable(amount.units="mg", time.units="hours") %>%

## Now solve
x <- predict(mod1,theta, ev, inits)
rxHtml(x)
``````

Solved RxODE object
Parameters (\$params):
V2 V3 KA CL Q Kin Kout EC50
40.2 297 0.294 18.6 10.5 1 1 200
Initial Conditions ( \$inits):
depot centr peri eff
0 0 0 1
First part of data (object):
time C2 C3 depot centr peri eff
0 0.00000 0.0000000 10000.000 0.000 0.0000 1.000000
1 44.37555 0.9198298 7452.765 1783.897 273.1895 1.084664
2 54.88296 2.6729825 5554.370 2206.295 793.8758 1.180825
3 51.90343 4.4564927 4139.542 2086.518 1323.5783 1.228914
4 44.49738 5.9807076 3085.103 1788.795 1776.2702 1.234610
5 36.48434 7.1774981 2299.255 1466.670 2131.7169 1.214742
or

``````x <- solve(mod1,theta, ev, inits)
rxHtml(x)
``````

Solved RxODE object
Parameters (\$params):
V2 V3 KA CL Q Kin Kout EC50
40.2 297 0.294 18.6 10.5 1 1 200
Initial Conditions ( \$inits):
depot centr peri eff
0 0 0 1
First part of data (object):
time C2 C3 depot centr peri eff
0 0.00000 0.0000000 10000.000 0.000 0.0000 1.000000
1 44.37555 0.9198298 7452.765 1783.897 273.1895 1.084664
2 54.88296 2.6729825 5554.370 2206.295 793.8758 1.180825
3 51.90343 4.4564927 4139.542 2086.518 1323.5783 1.228914
4 44.49738 5.9807076 3085.103 1788.795 1776.2702 1.234610
5 36.48434 7.1774981 2299.255 1466.670 2131.7169 1.214742

Or with `mattigr`

``````x <- mod1 %>% solve(theta, ev, inits)
rxHtml(x)
``````

Solved RxODE object
Parameters (\$params):
V2 V3 KA CL Q Kin Kout EC50
40.2 297 0.294 18.6 10.5 1 1 200
Initial Conditions ( \$inits):
depot centr peri eff
0 0 0 1
First part of data (object):
time C2 C3 depot centr peri eff
0 0.00000 0.0000000 10000.000 0.000 0.0000 1.000000
1 44.37555 0.9198298 7452.765 1783.897 273.1895 1.084664
2 54.88296 2.6729825 5554.370 2206.295 793.8758 1.180825
3 51.90343 4.4564927 4139.542 2086.518 1323.5783 1.228914
4 44.49738 5.9807076 3085.103 1788.795 1776.2702 1.234610
5 36.48434 7.1774981 2299.255 1466.670 2131.7169 1.214742

The solved object acts as a `data.frame` or `tbl` that can be filtered by `dpylr`. For example you could filter it easily.

``````library(dplyr)
``````
``````##
## Attaching package: 'dplyr'
``````
``````## The following objects are masked from 'package:stats':
##
##     filter, lag
``````
``````## The following objects are masked from 'package:base':
##
##     intersect, setdiff, setequal, union
``````
``````x <- mod1 %>% solve(theta,ev,inits) %>%  filter(time <=3)
x
``````
``````##   time       C2        C3     depot    centr      peri      eff
## 1    0  0.00000 0.0000000 10000.000    0.000    0.0000 1.000000
## 2    1 44.37555 0.9198298  7452.765 1783.897  273.1895 1.084664
## 3    2 54.88296 2.6729825  5554.370 2206.295  793.8758 1.180825
## 4    3 51.90343 4.4564927  4139.542 2086.518 1323.5783 1.228914
``````

However it isn't just a simple data object. You can use the solved object to update paramters on the fly, or even change the sampling time.

First we need to recreate the original solved system:

``````x <- mod1 %>% solve(theta,ev,inits);
``````

To examine or change initial conditions, you can use the syntax `cmt.0`, `cmt0`, or `cmt_0`. In the case of the `eff` compartment defined by the model, this is:

``````x\$eff0
``````
``````## [1] 1
``````

which shows the initial condition of the effect compartment. If you wished to change this initial condition to 2, this can be done easily by:

``````x\$eff0 <- 2
rxHtml(x)
``````

Solved RxODE object
Parameters (\$params):
V2 V3 KA CL Q Kin Kout EC50
40.2 297 0.294 18.6 10.5 1 1 200
Initial Conditions ( \$inits):
depot centr peri eff
0 0 0 2
First part of data (object):
time C2 C3 depot centr peri eff
0 0.00000 0.0000000 10000.000 0.000 0.0000 2.000000
1 44.37555 0.9198299 7452.765 1783.897 273.1895 1.496778
2 54.88295 2.6729829 5554.370 2206.295 793.8759 1.366782
3 51.90341 4.4564937 4139.542 2086.517 1323.5786 1.313536
4 44.49735 5.9807092 3085.103 1788.793 1776.2706 1.272430
5 36.48431 7.1774995 2299.255 1466.669 2131.7173 1.231204

Notice that the inital effect is now `2`.

You can also change the sampling times easily by this method by changing `t` or `time`. For example:

``````x\$t <- seq(0,5,length.out=20)
rxHtml(x)
``````

Solved RxODE object
Parameters (\$params):
V2 V3 KA CL Q Kin Kout EC50
40.2 297 0.294 18.6 10.5 1 1 200
Initial Conditions ( \$inits):
depot centr peri eff
0 0 0 2
First part of data (object):
time C2 C3 depot centr peri eff
0.0000000 0.00000 0.0000000 10000.000 0.0000 0.00000 2.000000
0.2631579 16.84421 0.0816880 9255.488 677.1371 24.26134 1.787179
0.5263158 29.52253 0.2985837 8566.406 1186.8059 88.67937 1.646825
0.7894737 38.85818 0.6148038 7928.627 1562.0986 182.59671 1.551517
1.0526316 45.52258 1.0016932 7338.331 1830.0078 297.50288 1.485338
1.3157895 50.06271 1.4364842 6791.983 2012.5211 426.63581 1.438438

You can also access or change parameters by the `\$` operator. For example, accessing `KA` can be done by:

``````x\$KA
``````
``````## [1] 0.294
``````

And you may change it by assigning it to a new value.

``````x\$KA <- 1;
rxHtml(x)
``````

Solved RxODE object
Parameters (\$params):
V2 V3 KA CL Q Kin Kout EC50
40.2 297 1 18.6 10.5 1 1 200
Initial Conditions ( \$inits):
depot centr peri eff
0 0 0 2
First part of data (object):
time C2 C3 depot centr peri eff
0.0000000 0.00000 0.0000000 10000.000 0.000 0.00000 2.000000
0.2631579 52.19463 0.2613582 7686.205 2098.224 77.62338 1.822345
0.5263158 83.29027 0.8999791 5907.775 3348.269 267.29379 1.737850
0.7894737 99.75845 1.7485784 4540.837 4010.290 519.32777 1.692658
1.0526316 106.29303 2.6926976 3490.181 4272.980 799.73120 1.665007
1.3157895 106.27096 3.6559925 2682.625 4272.092 1085.82977 1.644283

You can access/change all the parametrs, initilizations or events with the `\$params`, `\$inits`, `\$events` accessor syntax, similar to what is used above.

This syntax makes it easy to update and explore the effect of various parameters on the solved object.