Stop when a price history holds more than one index — check_one_index • golemstockindices

For the functions that work on one index at a time, so that a history of several indices gives a clear error instead of a wrong result.

Usage

check_one_index(history)

Arguments

history: Price history from get_history().

Value

history, invisibly, when it holds at most one index.

Examples

history <- data.frame(label = c("Alpha (A)", "Beta (B)"))
try(golemstockindices:::check_one_index(history))
#> Error : history holds 2 indices, keep one of them first, for example history[history$label == "Alpha (A)", ]