is_established_customerF <- function(customer_segment, credits_purchased) {
    print(typeof(customer_segment)) # prints only once?

    established_customer_threshold <- 100000000 # infinitely large
    customer_segment <- as.character(customer_segment)
    if (customer_segment == "multiple_photographer_company") {
        established_customer_threshold <- 3000
    } else if (customer_segment == "in_house_photography_department") {
        established_customer_threshold <- 1000
    } else if (customer_segment == "full_time_single_re_photographer") {
        established_customer_threshold <- 1000
    } else if (customer_segment == "part_time_single_re_photographer") {
        print("matched PT")

        established_customer_threshold <- 350
    } else if (customer_segment == "real_estate_agent") {
        print("matched RE")

        established_customer_threshold <- 150
    }

    # prints N times?
    print(paste(customer_segment, credits_purchased, ">", established_customer_threshold, credits_purchased > established_customer_threshold))

    return(credits_purchased > established_customer_threshold)
}

data[1:50][is_established_customerF(customer_segment, tx_cum_amount) == TRUE]

###
output
###
expect the `established_customer_threshold` to be different for these rows...
[20] "real_estate_agent 300 > 150 TRUE"                
[21] "full_time_single_re_photographer NA > 150 NA"