[R] loop through columns in a data frame

[Yuan, Keming (CDC/DDNID/NCIPC/DVP)]

Thank you so much, Jim. That’s exactly what I need. Sorry for not providing the data frame. But you created the correct data structure. Thanks again!

From: jim holtman <jholtman using gmail.com>
Sent: Monday, March 25, 2019 2:07 PM
To: Yuan, Keming (CDC/DDNID/NCIPC/DVP) <vrm4 using cdc.gov>
Cc: R-help using r-project.org
Subject: Re: [R] loop through columns in a data frame

R Notebook

You forgot to provide what your test data looks like. For example, are all the columns a single letter followed by “_" as the name, or are there longer names? Are there always matched pairs (‘le’ and ‘me’) or can singles occur?
Hide

library(tidyverse)

# create some data

test <- tibble(a_le = sample(3, 10, TRUE),

               a_me = sample(3, 10, TRUE),

               b_le = sample(3, 10, TRUE),

               b_me = sample(3, 10, TRUE),

               long_le = sample(3, 10, TRUE),

               long_me = sample(3, 10, TRUE),

               short_le = sample(3, 10, TRUE)

)

So get the names of the columns that contain ‘le’ or ‘me’ and group them together for processing
Hide

col_names <- grep("_(le|me)$", names(test), value = TRUE)

group <- tibble(id = str_remove(col_names, "_.*"), col = col_names)

result <- group %>%

  group_by(id) %>%

  do(tibble(x = rowSums(test[, .$col] == 1)))

# add new columns back

for (i in split(result, result$id)){

  test[, paste0(i$id[1], "_new")] <- as.integer(i$x > 0)

}

test


a_le
<int>

a_me
<int>

b_le
<int>

b_me
<int>

long_le
<int>

long_me
<int>

short_le
<int>

a_new
<int>

b_new
<int>

long_new
<int>

3

1

2

3

1

2

2

1

0

1

2

3

3

2

1

1

1

0

0

1

3

2

3

2

1

3

3

0

0

1

2

3

1

3

3

1

2

0

1

1

1

1

2

1

1

2

2

1

1

1

3

3

3

1

1

1

1

0

1

1

1

2

1

2

2

2

2

1

1

0

1

3

2

3

1

1

3

1

0

1

3

1

1

1

3

3

2

1

1

0

1

1

1

2

3

3

3

1

1

0

1-10 of 10 rows | 1-10 of 11 columns

Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.


On Mon, Mar 25, 2019 at 10:08 AM Yuan, Keming (CDC/DDNID/NCIPC/DVP) via R-help <r-help using r-project.org<mailto:r-help using r-project.org>> wrote:
Hi All,

I have a data frame with variable names like A_le, A_me, B_le, B_me, C_le, C_me....
if A_le=1 or A_me=1 then  I need to create a new column A_new=1. Same operation to create columns B_new, C_new...
Does anyone know how to use loop (or other methods) to create new columns? In SAS, I can use array to get it done. But I don't know how to do it in R.

Thanks,

Keming Yuan
CDC


        [[alternative HTML version deleted]]

______________________________________________
R-help using r-project.org<mailto:R-help using r-project.org> mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

	[[alternative HTML version deleted]]