Hi, R listers, I��m trying to compare a value of a row in a column to values of previous rows in another column in a loop. ��i�� is just from first row to the last row. j is an another looping controller indicating the rows that row[i] will be compared to and j will be rows before row[i]. I want to compare phone_1[i] with phone_2[j] and vise versa. for (i in 1: nrow(df)) { if (df$Incremental[i] == 1) {mark[i] <- 1} else {for (j in (i �C df$Incremental[i] + 1) : (i - 1)) { if ((df$Phone_1[i] != "" & df$Phone_1[i] == df$Phone_2[j]) | (df$Phone_2[i] != "" & df$Phone_2[i] == df$Phone_1[j])) { mark[i] <- mark[j]} else {mark[i] <- mark[i-1] + 1} } } However I��m getting an error with phone_1[i] and phone_2[j], indicating that ��level sets of factors are different��. I��m not sure what I need to do to fix it. Thanks! [[alternative HTML version deleted]]
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