Storing loop output from a function

From: Uwe Ligges

Andrew Kniss wrote:

I am attempting to write an R function to aid in time 

series diagnostics.

The tsdiag() works well, but I would prefer to get a plot 

with ACF, PACF,

and Ljung-Box p-values of residuals.  In my attempt to get 

to that point, I

am writing a function to calculate Ljung-Box p-values for 

residuals at

various lag distances.

ljung<-function(fit) 
       for(i in c(1:24,36,48))   
          {box<-(Box.test(fit$residuals, lag=i, type="Ljung-Box")) 
           print(c(i, box$p.value))}

You need to return() rather than print() the object.

Uwe Ligges

This is one of my first R function writing attempts, so my 

apologies if

there is an obvious mistake.  The above function produces 

the desired effect

in printing the lags and p-values to be plotted [where fit 

is the result of

arima()]; however I cannot seem to get the output stored in 

a data.frame for

subsequent plotting.  I have tried storing the output using 

various methods

including data.frame, write.table, cat, capture.output, all 

with no success.

e.g:
ljung.out<-capture.output(print(c(i, box$p.value)))  
#I saw a suggestion similar to this one in a previous post 

to the list...

  
Any hints on how I can get the output stored so that I may 

plot it later? I

am using v 1.9.1, RGui for Windows.
Thanks,
 
Andrew Kniss
Assistant Research Scientist
University of Wyoming
Dept. 3354  
1000 E. University Ave.
Laramie, WY  82071
(307) 766-3949
akniss at uwyo.edu


Below is an arima fit that I have used in testing the function.

dump("coal.fit", file=stdout())

coal.fit <-
structure(list(coef = structure(c(0.69539198614687, 484.903589344614
), .Names = c("ar1", "intercept")), sigma2 = 3109.45476265185, 
    var.coef = structure(c(0.0104024111201598, 0.302125085158484, 
    0.302125085158484, 634.39981868771), .Dim = as.integer(c(2, 
    2)), .Dimnames = list(c("ar1", "intercept"), c("ar1", 

"intercept"

    ))), mask = c(TRUE, TRUE), loglik = -266.892361376605, aic =
539.784722753209, 
    arma = as.integer(c(1, 0, 0, 0, 1, 0, 0)), residuals =
structure(c(60.4342567589239, 
    -127.383559378086, -14.9885854976147, 123.839062585504,
-56.6019914334983, 
    35.7247594443981, 63.6906479431108, -28.1651273226733,
-6.91856808459544, 
    8.90309567990135, -30.8784722646861, -91.1489687772519,
-103.345257968621, 
    -29.2770349660464, -20.9664426335713, -25.3512422872431, 
    32.6086618928476, -6.98260117899269, -108.850345082021,
4.60267757422564, 
    38.6146462114696, 42.7187751257762, 79.9491758184327, 

36.880952815858, 

    62.0132089128299, -0.848550671576206, -15.6420872534077, 
    111.955160137055, 13.5021374808082, -126.940710948639, 

63.7127908071542,

    27.4722158876983, -52.0448398629454, -15.4535767911051,
-73.4996569296364, 
    46.7008221699102, 27.5464232088949, -2.40151233395178,
-80.5337684309237, 
    -20.8162335807335, -18.2070175530272, -33.9885854976147, 
    -5.94848967770536, 17.8390625855041, 0.109559098069901,
39.5464232088949, 
    30.2537838322858, 32.9551601370546, 13.4381043864110), 

.Tsp = c(1, 

    49, 1), class = "ts"), call = stats:::arima(x = x, 

order = order, 

        seasonal = seasonal, include.mean = include.mean), 

series = "x", 

    code = as.integer(0), n.cond = 0, model = structure(list(
        phi = 0.69539198614687, theta = numeric(0), Delta = 

numeric(0), 

        Z = 1, a = 60.0964106553856, P = structure(0, .Dim 

= as.integer(c(1,

        1))), T = structure(0.69539198614687, .Dim = 

as.integer(c(1, 

        1))), V = structure(1, .Dim = as.integer(c(1, 1))), h = 0, 
        Pn = structure(1, .Dim = as.integer(c(1, 1)))), 

.Names = c("phi", 

    "theta", "Delta", "Z", "a", "P", "T", "V", "h", "Pn")), x =
structure(as.integer(c(569, 
    416, 422, 565, 484, 520, 573, 518, 501, 505, 468, 382, 310, 
    334, 359, 372, 439, 446, 349, 395, 461, 511, 583, 590, 620, 
    578, 534, 631, 600, 438, 516, 534, 467, 457, 392, 467, 500, 
    493, 410, 412, 416, 403, 422, 459, 467, 512, 534, 552, 545
    )), .Dim = as.integer(c(49, 1)), .Dimnames = list(NULL, 

"Coal"), .Tsp =

c(1, 
    49, 1), class = "ts")), .Names = c("coef", "sigma2", 

"var.coef", 

"mask", "loglik", "aic", "arma", "residuals", "call", "series", 
"code", "n.cond", "model", "x"), class = "Arima")