[R] How to show variables used in lm function call?

Pele drdionc at yahoo.com
Tue Feb 3 18:16:43 CET 2009


Hello R users,

I am new to R and am wondering if anyone can help me out 
with the following issue: I wrote a function to build ts models using
different inputs, but when R displays the call for a model, I cannot tell
which variables 
it is using because it shows the arguments instead of the real variables
passed to the function. 

(e.g 

Call:
lm(formula = dyn(dep ~ lag(dep, -1) + indep)) ---> not what I want to see

lm(formula = dyn(Y ~ lag(Y, -1) + XVARY))   -----> this is what I want to
see 


(see simplified version of the code and output below)

Thanks in advance for any help!!


 
options (scipen=999, digits=7)

library(Hmisc)
library(DAAG)
library(car)
library(MASS)
library(nlme)
library(dyn)
library(zoo)

tdata <- ts(read.table("C:/R/testing/data.csv" ,sep = ",",header=TRUE))
print(tdata)

coeff <- function(dep, indep) {
  mod    <- dyn$lm(dep ~ lag(dep, -1)+ indep)
  summ   <- summary(mod)
  res    <- list(COEF=summ)    }

  out    <- coeff(tdata[ ,"Y"], tdata[ ,"XVARY"]); out

#########output#############

>  print(tdata)
Time Series:
Start = 1 
End = 20 
Frequency = 1 
   Unit  Y XVARY  K DWAY
 1    1  3     2  4   50
 2    2  5     3  9   50
 3    3  6    11 22   50
 4    4  8     4  7    2
 5    5  9    11 11    2
 6    6 12    13 13    2
 7    7 23    25 12    2
 8    8 22    30 31    3
 9    9 23     3  3    3
10   10 19    21 21   32
11   11  3     2  4   34
12   12  5     3  9    4
13   13  6    11 22    4
14   14  8     4  7    4
15   15  9    11 11    4
16   16 12    13 13    4
17   17 23    25 12    4
18   18 22    30 31    4
19   19 23     3  3    4
20   20 19    21 21    5
> 
>    coeff <- function(dep, indep) {
+    
+    mod    <- dyn$lm(dep ~ lag(dep, -1)+ indep)
+    summ   <- summary(mod)
+    res    <- list(COEF=summ) }
> 
> out       <- coeff(tdata[ ,"Y"], tdata[ ,"XVARY"]); out
$COEF

Call:
lm(formula = dyn(dep ~ lag(dep, -1) + indep))

Residuals:
     Min       1Q   Median       3Q      Max 
-10.7157  -2.5454  -0.2090   0.8359   7.3292 

Coefficients:
             Estimate Std. Error t value Pr(>|t|)   
(Intercept)    2.6473     2.1952   1.206  0.24538   
lag(dep, -1)   0.5506     0.1558   3.535  0.00275 **
indep          0.3033     0.1259   2.408  0.02845 * 
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 4.643 on 16 degrees of freedom
  (2 observations deleted due to missingness)
Multiple R-squared: 0.6679,     Adjusted R-squared: 0.6264 
F-statistic: 16.09 on 2 and 16 DF,  p-value: 0.0001479 

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