left_join with by.x and by.y

[Mrostgaard]

Hello

So I have some R code that looks like this:

new_df = df1 %>% merge(df2, by.x = "col", by.y = "col2", all.x = TRUE)
I'm trying to merge left with two columns. Both have by.y value (col2) but only df1 have col1 value.
When I try to do it the datar way like this:
new_df = df1 >> left_join(df2, by =["col1", "col2"])

I get the error:
KeyError: 'col1'

Am I doing something wrong? Or is it not possible to do by.x, by.y like in R?

When doing it the pandas way like:

new_df = pd.merge(df1, df2, left_on = "col1", right_on = "col2", how="left")

It returns col2_y and col2_x, which I'm not interested in. This is not a problem in the R code

[pwwang]

You need to use dict for the column mapping:

See also examples at:

https://pwwang.github.io/datar/notebooks/mutate-joins/

[Mrostgaard]

Doing that returns KeyError {'col2', 'col1'} (in that order)
Adding keep=True return: KeyError: 'col1_y'

[pwwang]

Do you have an example dataset that I can investigate?

[Mrostgaard]

@pwwang I'm sorry, but I'm unfortunately not at liberty to share the datasets. My question was mostly aimed at founding out whether or not, there was something in the documentation I had missed. I will just have to see if I can do it some other way 🙂 Once again I appreciate your insanely quick response time

[pwwang]

No problem at all. You can also play with that notebook on binder to see if it works in your case.

[Mrostgaard]

Thank you for that

[pwwang]

I assume this is solved. If problem still persists, feel free to reopen.