[英]R - assigning value to one column based on a comparison of two other columns
假設我有以下數據:
SNP eff_allele A1 A2
rs1000000 A A G
rs10000010 C C T
rs1000002 T T C
rs10000023 G T G
我想創建一個新的變量alt_allele,該變量采用列A1或A2的值,具體取決於列eff_allele的值。 如果eff_allele等於A1,則alt_allele應獲取A2的值,如果eff_allele等於A2,則alt_allele應獲取A1的值。 我做了兩次嘗試:
嘗試1:
if (myData$eff_allele == myData$A1) {
myData$alt_allele <- myData$A2
}
if (myData$eff_allele == myData$A2) {
myData$alt_allele <- myData$A1
}
嘗試2:
height_fam$alt_allele[height_fam$eff_allele == height_fam$A1] <- height_fam$A2
height_fam$alt_allele[height_fam$eff_allele == height_fam$A2] <- height_fam$A1
這兩個都不起作用...我在做什么錯? 如何實現對數據的以下更新:
SNP eff_allele A1 A2 alt_allele
rs1000000 A A G G
rs10000010 C C T T
rs1000002 T T C C
rs10000023 G T G T
在R
和matlab
盡量不要使用循環,它們比較慢。 嘗試通過向量 s解決您的問題。
編輯 :哦,我讀錯了您的問題,無論如何您都沒有使用向量:)
a=read.table("a.csv", sep = " ", header = T)
row = dim(a)
# Number of rows
row = row[2]
newcol = rep("",row)
A1 = as.character(a$A1)
A2 = as.character(a$A2)
eff_allele = as.character(a$eff_allele)
# a1_ind is FALSE for index that should be equal to A1
a1_ind = eff_allele!= A1
newcol[a1_ind] = A1[a1_ind]
newcol[!a1_ind] = A2[!a1_ind]
a = cbind(a,newcol)
輸出將是:
SNP eff_allele A1 A2 newcol
1 rs1000000 A A G G
2 rs10000010 C C T T
3 rs1000002 T T C C
4 rs10000023 G T G T
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