r - Looping over column names like DF$j -
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i have following data frame:
id a1 a2 a3 a4 b1 b2 b3 b4 1 id1 1 2 1 1 1 1 2 2 2 id2 2 2 1 1 2 na 2 1 3 id3 2 2 1 2 1 1 na 2 4 id4 1 1 1 1 1 na na 2 5 id5 2 2 1 1 na na 2 na 6 id6 1 1 1 1 2 2 2 2 i want extract rows data frame meeting specific conditions each combination of , b. these conditions:
pp: value 2 present in a-type column + value 2 present in b-type column
pa: value 2 present in a-type column + value 1 present in b-type column
ap: value 1 present in a-type column + value 2 present in b-type column
aa: value 1 present in a-type column + value 1 present in b-type column
this wrote:
a <- colnames(dataframe)[2:5] # = a1, a2, a3 , a4 b <- colnames(dataframe)[6:9] # b = b1, b2, b3 , b4 (a in a) { (b in b) { pp <- dataframe[dataframe$a=='2' & dataframe$b=='2' , ] pa <- dataframe[dataframe$a=='2' & dataframe$b=='1' , ] ap <- dataframe[dataframe$a=='1' & dataframe$b=='2' , ] aa <- dataframe[dataframe$a=='1' & dataframe$b=='1' , ] print(head(pp)) #to have preview } } however new data frames empty , don't understand why. ideally, the first loop (with a=a1 , b=b1) therefore output:
pp:
id a1 a2 a3 a4 b1 b2 b3 b4 2 id2 2 2 1 1 2 na 2 1 pa:
id a1 a2 a3 a4 b1 b2 b3 b4 3 id3 2 2 1 2 1 1 na 2 ap:
id a1 a2 a3 a4 b1 b2 b3 b4 6 id6 1 1 1 1 2 2 2 2 aa:
id a1 a2 a3 a4 b1 b2 b3 b4 1 id1 1 2 1 1 1 1 2 2 i hope can help. thanks.
the dollar sign extraction creating problem. not meant passing of variables in dataframe$a. because a not actual name. trying pass variable name on it. operator literal a column , not find it. try dataframe[,a]
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