My previous question put in a simpler way: How would I pass a value of a variable to a function such as
lm(Effect1~Trt*Dose, data = x, contrasts = list(Trt = contr.sum, Dose = contr.sum))? Here, 'Effect' is a column name in my data matrix, and I want "Effect1" to be replaced by "Effect2" and so on (my other column names in the data frame) for successive anova calculations. So I am storing the column names as an array, and passing the array as a parameter to the lm() function. Thanks, ----- Forwarded by Subramanian Karthikeyan/HC-SC/GC/CA on 2003-10-22 01:47 PM ----- Subramanian Karthikeyan To: [EMAIL PROTECTED] cc: 2003-10-22 01:31 Subject: providing a variable as a parameter in a function PM >From a data frame, how do we extract a specific column name, and plug that into a command (eg. for Anova as shown below) > df = read.delim("mydata.txt") > y = colnames(df) > r = ncol(x) Lets say that in the data frame column 1 contains treatments, column 2 contains doses, and columns 3, 4, 5 etc. are different responses, and I want to run separate 2-way anovas for each response, i.e. my first anova will be done using col 1: Treatment, col 2: Dose and Col 3: a response, second anova will be done using treatment (col1), dose (col2) and another response (col 4) and so on. I could use a loop to automate the task. > for (i in 3:r) { + mod = lm(y[i]~Trt*Dose, data = x, contrasts = list(Trt = contr.sum, Dose = contr.sum)) + Anova(mod, type = "III") + } The problem is when I directly plug in y[3] for my response variables name, it gives me an error Error in model.frame(formula, rownames, variables, varnames, extras, extranames, : invalid variable type This is likely because the lm() function wants the actual column name, rather than a variable containing the column name. Can someone advice? Thanks, Karth. ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help