R语言实现对基因组SNV进行注释

 1 fregion <- function(df, value){
 2 #df:data.frame, V1 and V2 should be Start and End   value: Postition  used to find region  return:df row number where position locates  ,if no region return -1
 3     low=1
 4     high=nrow(df)
 5     mid=high %/% 2
 6     if (df[low,1] <= value & value <= df[low,2]) low
 7     else if (df[high,1] <= value & value <= df[high,2]) high
 8     else{
 9     while (value > df[mid,2] || value < df[mid,1]){
10       if (value > df[mid,2]){
11         low = mid+1
12       } else if (value < df[mid,1]) {
13         high = mid - 1
14       } 
15       if(high<low){
16          mid=-1;break
17       }
18       mid=(low+high)%/%2
19     }
20       mid
21 }
22 }