R - Error in For Loops and If Statements on list of Data Frames: Subscript Out of Bounds -

i'm using r create occupancy model encounter history. need take list of bird counts individual leks, separate them year, code count dates 2 intervals, either within 10 days of first count (interval 1), or after 10 days after first count (interval 2). year 1 count occurred need add entry coded "u", indicate no count occurred during second interval. following need subset out max count in each year , interval. sample dataset:

 complexid       date males year category         57 1941-04-15    97 1941                57 1942-04-15    67 1942                57 1943-04-15    44 1943                57 1944-04-15    32 1944                57 1946-04-15    21 1946                57 1947-04-15    45 1947                57 1948-04-15    67 1948                57 1989-03-21    25 1989                57 1989-03-30    41 1989                57 1989-04-13     2 1989                57 1991-03-06    35 1991                57 1991-04-04    43 1991                57 1991-04-11    37 1991                57 1991-04-22    25 1991                57 1993-03-23     6 1993                57 1994-03-06    17 1994                57 1994-03-11    10 1994                57 1994-04-06    36 1994                57 1994-04-15    29 1994                57 1994-04-21    27 1994        

now here code wrote accomplish task, naming dataframe above "c1" (you'll need coerce date column date, , category column character):

c1_year<-lapply(unique(c1$year), function(x) c1[c1$year == x,]) #splits complex counts list year  for(i in 1:length(c1_year)){   c1_year[[i]]<-cbind(c1_year[[i]], daydiff = as.numeric(c1_year[[i]][,2]-c1_year[[i]][1,2])) } #adds column difference between first survey , subsequent surveys  for(i in 1:length(c1_year)){   c1_year[[i]]<-if(length(c1_year[[i]][,1]) == 1)     rbind(c1_year[[i]], c(c1_year[[i]][1,1], na, 0, c1_year[[i]][1,4], "u", 11))  } # adds u values years 1 count,  while coercing "u" appropriate interval  for(i in 1:length(c1_year)){   c1_year[[i]]$interval<- ifelse(c1_year[[i]][,6] < 10, 1, 2) } # adds interval code each survey, 1 = less ten days after first count, 2 = more 2 days after count  for(i in 1:length(c1_year)){   c1_year[[i]]<-ddply(.data=c1_year[[i]], .(interval), subset, males==max(males))  } # subsets out max count in each interval 

the problem arises during second for-loop, when options(error=recover) enable returns: error in c1_year[[i]] : subscript out of bounds no suitable frames recover() ` @ point code accomplishes supposed , adds line each year 1 count, though error message generated rows "u" code still appended data frames. issue have 750 leks for. tried build code above function, when run function on data subscript out of bounds error stops function running. brute force , run code above each lek manually, hoping there might more elegant solution. need know why getting subscript out of bounds error, , how can fix it?

here's function wrote, can see doesn't work:

create.oeh<-function(dataset, final_dataframe){   c1_year<-lapply(unique(dataset$year), function(x) dataset[dataset$year == x,]) #splits complex counts list year    for(i in 1:length(c1_year)){     c1_year[[i]]<-cbind(c1_year[[i]], daydiff = as.numeric(c1_year[[i]][,2]-c1_year[[i]][1,2]))   } #adds column difference between first survey , subsequent surveys    for(i in 1:length(c1_year)){     c1_year[[i]]<-if(length(c1_year[[i]][,1]) == 1)       rbind(c1_year[[i]], c(c1_year[[i]][1,1], na, 0, c1_year[[i]][1,4], "u", 11))    } # adds u values years 1 count,    for(i in 1:length(c1_year)){     c1_year[[i]]$interval<- ifelse(c1_year[[i]][,6] < 10, 1, 2)   } # adds interval code each survey, 1 = less ten days after first count, 2 = more 2 days after count    for(i in 1:length(c1_year)){     c1_year[[i]]<-ddply(.data=c1_year[[i]], .(interval), subset, males==max(males))    } #subset out max count each interval    df<-rbind.fill(c1_year) #collapse list single dataframe    final_dataframe<-df[!duplicated(df[,c("year", "interval")]),] #remove ties max count  } 

in bit of code

for(i in 1:length(c1_year)){     c1_year[[i]]<-if(length(c1_year[[i]][,1]) == 1)       rbind(c1_year[[i]], c(c1_year[[i]][1,1], na, 0, c1_year[[i]][1,4], "u", 11))    }  

you assigning null if length(c1_year[[i]][,1]==1 not true, removes elements c1_year entirely.

you want

for(i in 1:length(c1_year)){     if (length(c1_year[[i]][,1]) == 1) {         c1_year[[i]] <- rbind(c1_year[[i]], c(c1_year[[i]][1,1], na, 0, c1_year[[i]][1,4], "u", 11))      }   }  

however, see using ddply, may able avoid lot of replication. ddply(c1, .(year), ...) splits c1 unique years.

c2 <- ddply(c1,             .(year),             function (x) {                 # create 'interval'                 x$interval <- ifelse(x$date - x$date[1] < 10, 1, 2)                 # extract max males per interval                 o <- ddply(x, .(interval), subset, males==max(males))                 # add 'u' col if no '2' interval                 if (all(o$interval != 2)) {                     o <- rbind(o,                                list(o$complexid, na, 0, o$year, 'u', 2))                 }                 # return resulting dataframe                 o             }) 

i converted rbind(.., c(...)) rbind(.., list(...)) avoid converting string (which c because cannot handle multiple different types).

otherwise code same yours.