Writing R functions to support vectors -

i have function:

pcal.getperiodfordate <- function(date_) {     dateobject <- as.posixlt(date_)     calendarstart <- pcal.getcalendarstart(dateobject$year + 1900)      difference <- dateobject - calendarstart      if(difference < 0) {         calendarstart <- pcal.getcalendarstart(dateobject$year + 1899)         difference <- dateobject - calendarstart     }      period <- difference / 28      week <- ifelse(period < 1, ceiling(period * 4), ceiling((period - floor(period)) * 4))      return(list(period = as.numeric(ceiling(period)), week = week)) } 

i have data frame following structure

> str(sells) 'data.frame':   73738 obs. of  4 variables:  $ loc_nbr: chr  "2" "2" "2" "2" ...  $ sls_dt : date, format: "2015-02-01" "2015-02-02" "2015-02-03" "2015-02-04" ...  $ sales  : num  1 2 3 4 5 ... 

i want able this:

sells$pd <- pcal.getperiodfordate(sells$sls_dt)$period 

however, ton of warnings:

warning messages: 1: in if (year < 2000) { :   condition has length > 1 , first element used 2: in seedyear:year :   numerical expression has 73738 elements: first used 3: in if (difference < 0) { :   condition has length > 1 , first element used 4: in if (year < 2000) { :   condition has length > 1 , first element used 5: in seedyear:year :   numerical expression has 73738 elements: first used 

the function works fine passing 1 value:

> pcal.getperiodfordate('2015-09-29') $period [1] 9  $week [1] 3 

how can make work?

the function if not vectorized in r means can use vectors of length 1. using if bigger vectors cause warnings serious warning should not ignored if uses first element of vector cause trouble. see simple case:

> if(c(1,-5,3) > 0) print('hello') [1] "hello" warning message: in if (c(1, -5, 3) > 0) print("hello") :   condition has length > 1 , first element used 

in case although there -5 in vector above hello returned because if checks first element of vector.

in order use if vector have 3 options:

all

use function all when want every element of vector confirm condition:

if( all(c(1,-5,3) > 0) ) print('hello') #this not return 

any

use function any when want @ least 1 of elements confirm condition:

> if( any(c(1,-5,3) > 0) ) print('hello') [1] "hello" 

apply family

use *apply family when need vector same size 1 in check (c(1,-5,3) here) each element checked against condition:

> vapply(c(1,-5,3), function(x) {    if (x > 0) 'hello' else na_character_  },   character(1)) [1] "hello" na      "hello" 

i cannot run function tell version of above need not know how difference used or pcal.getcalendarstart should enough fix warnings get. use 1 of above according how want if behave , should no warnings.