How can I use summary() with lqmm and formula objects - r

Question

I've got a list of formula objects to fit Linear Quantile Mixed Models with lqmm::lqmm().
I cannot use summary() to return model coefficients with standard errors etc. from the produced models.
d <- structure(list(DID = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), pain = c(4L, 2L, 6L, 3L, 3L,
4L, 3L, 3L, 4L, 5L, 4L, 4L, 5L, 3L, 4L, 3L, 2L, 6L, 5L, 7L, 6L,
3L, 5L, 1L, 5L, 3L, 4L, 4L, 6L, 5L, 5L, 6L, 5L, 6L, 5L, 6L, 6L,
5L, 6L, 7L, 4L, 5L, 6L, 6L, 5L, 6L, 4L, 5L, 6L, 7L), wound = c(4L,
3L, 3L, 3L, 4L, 5L, 4L, 3L, 4L, 4L, 3L, 3L, 3L, 3L, 3L, 4L, 3L,
4L, 4L, 3L, 3L, 3L, 4L, 3L, 3L, 4L, 5L, 3L, 8L, 7L, 7L, 7L, 7L,
9L, 8L, 8L, 8L, 6L, 7L, 6L, 8L, 7L, 6L, 8L, 7L, 6L, 7L, 8L, 7L,
7L), mobility = c(2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L,
3L, 3L, 2L, 1L, 1L, 2L, 2L, 3L, 2L, 3L, 1L, 2L, 2L, 3L, 2L, 3L,
3L, 6L, 5L, 6L, 6L, 5L, 6L, 5L, 5L, 5L, 5L, 6L, 5L, 6L, 5L, 5L,
5L, 6L, 5L, 5L, 3L, 5L, 6L)), row.names = c(NA, 50L), class = "data.frame")
library(lqmm)
x <- as.formula("pain ~ wound + mobility")
m1 <- lqmm(x,
random = ~ 1,
group = DID,
data = d)
summary(m1)
Error: object of type 'symbol' is not subsettable
I tried using eval(x) as suggested here, but got a recursion error.
m2 <- lqmm(eval(x),
random = ~ 1,
group = DID,
data = d)
summary(m2)
Error: evaluation nested too deeply: infinite recursion / options(expressions=)?
Error during wrapup: evaluation nested too deeply: infinite recursion / options(expressions=)?
Error: no more error handlers available (recursive errors?); invoking 'abort' restart
Any ideas on how to extract model parameters?
Full sample data was taken from here.

Answer 1

Run this like below, It should work:
x <- as.formula('pain ~ wound + mobility')
m1 <- lqmm(x,
random = ~ 1,
group = DID,
data = d)
## Fixing the call fixed here.
m1$call$fixed <- x
summary(m1)
Output:
> m1$call$fixed <- x
> summary(m1)
Call: lqmm(fixed = pain ~ wound + mobility, random = ~1, group = DID,
data = d)
Quantile 0.5
Fixed effects:
Value Std. Error lower bound
(Intercept) 2.765900 1.294809 0.163883
wound 0.052025 0.077028 -0.102770
mobility 0.469649 0.127371 0.213687
upper bound Pr(>|t|)
(Intercept) 5.3679 0.0376887 *
wound 0.2068 0.5025982
mobility 0.7256 0.0005675 ***
---
Signif. codes:
0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
AIC:
[1] 166.1 (df = 5)
There is catch after little debug, I realised objects returned by below two approaches are not similar hence I have manipulated one of them like above:
m2 <- lqmm(pain ~ wound + mobility,
random = ~ 1,
group = DID,
data = d)
m1 <- lqmm(x,
random = ~ 1,
group = DID,
data = d)
If we closely observe m1$call and m2$call,(m1 is working well with summary) however, both are different objects and hence leading to the error which OP has encountered, I think its a bug but please let me know if there is any other explanation. Also while running all.equal(m1, m2) it tells me there is indeed a difference. So, after fiddling it with the given info, I have resetted the fixed element of list to original x (which is formula), which it seems to be working for now:
> all.equal(m1, m2)
[1] "Component “call”: target, current do not match when deparsed"