Why is R code that works fine in R not working in Alteryx

[seungp]

Why is R code that works in R not working in Alteryx R?? 

I am copying my code from R that I've written using for loop to R in Alteryx and it's giving me an error. 

I am not using any packages, but I am using for loop to make calculations to replace rows with Nulls using data in data frame. The code works fine in R and I get all the calculations I need, and when I copy the code over to R in Alteryx, it's giving me an error. 

Sample code:

for (i in 2:nrow(test)) {
test$new[i] = (test$new[i-1] * (1 + test$growth[i-1]))
}

Error message:

Error in test$new[i] = (test$new[i-1] * (1 + test$growth[i-1]))

replacement has length zero

If I can't just copy over the code from R, what's the benefit of having R in Alteryx?

[danilang]

Hi @seungp 

How are you passing in test to the R tool?  Can you attach a sample workflow?

Dan

[seungp]

So I have data imported as an input from database structured like

date	new	growth
2021/02/01	1000	0.01
2021/02/02	NA	0.01
2021/02/03	NA	0.02
2021/02/04	NA	0.02

This is just sample data, but I have a dates column, new column that has value for only the first row, and growth column that can have different growth for different dates.

I am querying this data frame from my database and calling it a test in Alteryx. 

The goal I'm trying to achieve using R in Alteryx is filling out NAs in new column with calculation shown in my previous post. 

[danilang · Accepted solution]

Hi @seungp 

Here's a workflow that works using the R tool

Here's the code in that's in the R tool

test = read.Alteryx("#1", mode="data.frame") #Read data from Alteryx

for (i in 2:nrow(test)) {
  test$new[i] = (test$new[i-1] * (1 + test$growth[i-1]))
}

write.Alteryx(test, 1)  #Write results back to alteryx

 As you can see once you add in the function calls to read in the data as a dataframe and write the results back out, the code works correctly. 

One thing to note is that the read.Alteryx() returns a typed dataframe, so the [new] column is a string and your code as written can't perform the math operations on string fields.  I deleted the NA in the input data and forced the datatype to double.

The Multi-Row tool is there just to show how to perform the same operation in native Alteryx.  There's a small overhead to invoking the R runtime .  If your data set is small, the overall workflow will run faster if you can perform the task using native Alteryx tools

Dan