IRKernel prints data.table with :=

[matthieugomez]

It's basically the same issue than with knitr. I have printed the variable SYS (at line 82 of data.table.R) after a command such as DT[, a:=1] in IRKernel but I don't know enough to do a pull request.

[[1]]
IRkernel::main()

[[2]]
kernel$run()

[[3]]
handle_shell()

[[4]]
executor$execute(msg)

[[5]]
with_top_env(userenv, {
    tryCatch(evaluate(request$content$code, envir = userenv, 
        output_handler = oh, stop_on_error = 0), interrupt = function(cond) {
        interrupted <<- TRUE
    }, error = handle_error)
})

[[6]]
tryCatch(evaluate(request$content$code, envir = userenv, output_handler = oh, 
    stop_on_error = 0), interrupt = function(cond) {
    interrupted <<- TRUE
}, error = handle_error)

[[7]]
tryCatchList(expr, classes, parentenv, handlers)

[[8]]
tryCatchOne(tryCatchList(expr, names[-nh], parentenv, handlers[-nh]), 
    names[nh], parentenv, handlers[[nh]])

[[9]]
doTryCatch(return(expr), name, parentenv, handler)

[[10]]
tryCatchList(expr, names[-nh], parentenv, handlers[-nh])

[[11]]
tryCatchOne(expr, names, parentenv, handlers[[1L]])

[[12]]
doTryCatch(return(expr), name, parentenv, handler)

[[13]]
evaluate(request$content$code, envir = userenv, output_handler = oh, 
    stop_on_error = 0)

[[14]]
evaluate_call(expr, parsed$src[[i]], envir = envir, enclos = enclos, 
    debug = debug, last = i == length(out), use_try = stop_on_error != 
        2L, keep_warning = keep_warning, keep_message = keep_message, 
    output_handler = output_handler)

[[15]]
handle(pv <- withCallingHandlers(withVisible(value_fun(ev$value, 
    ev$visible)), warning = wHandler, error = eHandler, message = mHandler))

[[16]]
try(f, silent = TRUE)

[[17]]
tryCatch(expr, error = function(e) {
    call <- conditionCall(e)
    if (!is.null(call)) {
        if (identical(call[[1L]], quote(doTryCatch))) 
            call <- sys.call(-4L)
        dcall <- deparse(call)[1L]
        prefix <- paste("Error in", dcall, ": ")
        LONG <- 75L
        msg <- conditionMessage(e)
        sm <- strsplit(msg, "\n")[[1L]]
        w <- 14L + nchar(dcall, type = "w") + nchar(sm[1L], type = "w")
        if (is.na(w)) 
            w <- 14L + nchar(dcall, type = "b") + nchar(sm[1L], 
                type = "b")
        if (w > LONG) 
            prefix <- paste0(prefix, "\n  ")
    }
    else prefix <- "Error : "
    msg <- paste0(prefix, conditionMessage(e), "\n")
    .Internal(seterrmessage(msg[1L]))
    if (!silent && identical(getOption("show.error.messages"), 
        TRUE)) {
        cat(msg, file = stderr())
        .Internal(printDeferredWarnings())
    }
    invisible(structure(msg, class = "try-error", condition = e))
})

[[18]]
tryCatchList(expr, classes, parentenv, handlers)

[[19]]
tryCatchOne(expr, names, parentenv, handlers[[1L]])

[[20]]
doTryCatch(return(expr), name, parentenv, handler)

[[21]]
withCallingHandlers(withVisible(value_fun(ev$value, ev$visible)), 
    warning = wHandler, error = eHandler, message = mHandler)

[[22]]
withVisible(value_fun(ev$value, ev$visible))

[[23]]
value_fun(ev$value, ev$visible)

[[24]]
value_handler(x)

[[25]]
paste(capture.output(print(obj)), collapse = "\n")

[[26]]
capture.output(print(obj))

[[27]]
evalVis(expr)

[[28]]
withVisible(eval(expr, pf))

[[29]]
eval(expr, pf)

[[30]]
eval(expr, envir, enclos)

[[31]]
print(obj)

[[32]]
print.data.table(obj)

[mattdowle]

Can this be closed now as it was from 2014 before the changes in v1.9.6 released in Sep 2015.

Although, something related has been raised recently as well :
https://github.com/IRkernel/IRkernel/issues/127#issuecomment-203070341

[jankatins]

irkernel prints via the repr package, i.e. repr_text.default() (source) or repr_text.matrix (source) If the latter, it is also printed by repr_html.matrix, repr_markdown.matrix and repr_latex.matrix . IMO the same workaround as for knit_print.default should go in here:

data.table/R/data.table.R

Line 35 in d356700

if (length(SYS) <= 2 || # "> DT" auto-print or "> print(DT)" explicit print (cannot distinguish from R 3.2.0 but that's ok)

Or make that a similar list as

data.table/R/cedta.R

Line 4 in 9d2d710

cedta.pkgEvalsUserCode = c("gWidgetsWWW","statET","FastRWeb","slidify","rmarkdown","knitr", "IRkernel")

so we can contribute to that list.

Or build and export repr_xxx.data.frame methods which only spit out a string representation if print would print the data.table (is that possible?)

cc: @flying-sheep

[mattdowle]

@JanSchulz Ok good idea. Thanks for investigating. Happy to try the simpler one first and see if it works ("making it a similar list as"). Will do.

[mattdowle]

Current status : https://github.com/IRkernel/IRkernel/issues/127#issuecomment-220479914

[mattdowle]

New status: https://github.com/IRkernel/IRkernel/issues/127#issuecomment-221957831

[MichaelChirico]

Just tried this on JupyterLab, it seems OK?

Closing ...