從另一個數據框中選擇具有相同特徵的元素？

Question

我在r中一個數據幀和我子集成兩個：

p<-c(3.14,3.56,7.45,8.33,5.44,3.12,3.78,7.62,9.12,4.34,6.78,8.65,6.99) 
n<-c("mQTL","mQTL","null","null","null","null","null","null","null","null","null","null","null") 
s<-c(2,2,1,2,1,1,2,2,2,1,2,1,2) 
g<-c("female","male","female","male","female","female","male","female","female","male","female","female","female") 
df<-data.frame(n,g,s,p) 
df 


mQTL<-subset(df,df$n=='mQTL') 

mQTL

n  g s p 
1 mQTL female 2 3.14 
2 mQTL male 2 3.56 


null<-subset(df,df$n=="null") 

空

n  g  s p 
3 null female 1 7.45 
4 null male 2 8.33 
5 null female 1 5.44 
6 null female 1 3.12 
7 null male 2 3.78 
8 null female 2 7.62 
9 null female 2 9.12 
10 null male 1 4.34 
11 null female 2 6.78 
12 null female 1 8.65 
13 null female 2 6.99 

我想隨機搜索從空兩個元件，其中每個的它們匹配基於性別（df $ g）和數量（df $ s）的兩個mQTL

例如，我想有這樣的事情第一個隨機畫

n g  s p 
null female 2 7.62 
null male 2 3.78 

第二隨機畫

n g  s p 
null female 2 9.12 
null male 2 3.78 

我想隨機得出這樣的5倍，例如，得到5不同的組合

我試圖

null[which((mQTL$g==null$g)& (mQTL$s==null$s)),] 

，但它給了我一個datafram所有的人都沒有兩屆組合電子

 n  g s p 
4 null male 2 8.33 
9 null female 2 9.12 
11 null female 2 6.78 
13 null female 2 6.99 

Answer 1

mQTL = subset(df,df$n=='mQTL') 
null = subset(df,df$n=='null') 

# Check if the combination of null$g and null$s matches with that of mQTL$g and mQTL$s 
null$match = paste(null$g, null$s) %in% paste(mQTL$g, mQTL$s) 

# Random sample of two of the matched rows 
null[sample(which(null$match), 2),] 

# > null[sample(which(null$match), 2),] 
#  n  g s p match 
# 13 null female 2 6.99 TRUE 
# 4 null male 2 8.33 TRUE 

要繪製的5倍，你運行一個for循環和存儲在列表得出：

draws = list() 
for(ii in 1:5){ 
    draws[[ii]] = null[sample(which(null$match), 2),] 
} 

# > draws 
# [[1]] 
#  n  g s p match 
# 4 null male 2 8.33 TRUE 
# 13 null female 2 6.99 TRUE 
# 
# [[2]] 
#  n  g s p match 
# 11 null female 2 6.78 TRUE 
# 9 null female 2 9.12 TRUE 
# 
# [[3]] 
#  n  g s p match 
# 9 null female 2 9.12 TRUE 
# 8 null female 2 7.62 TRUE 
# 
# [[4]] 
#  n  g s p match 
# 13 null female 2 6.99 TRUE 
# 4 null male 2 8.33 TRUE 
# 
# [[5]] 
#  n  g s p match 
# 7 null male 2 3.78 TRUE 
# 8 null female 2 7.62 TRUE 

Answer 2

嘗試使用merge()功能：

merge(mQTL, null, by.x = c("g","s"), by.y = c("g","s)) 

但你可能要重命名的列，使事情clearier。