dplyr_0.5.0.9002, passing string as variable name to select

[msquatrito]

Hi, 

I'm trying to pass a string as a variable name to `select()`. It works fine with `select_()`, however, now it is deprecated.

I'm not sure how to do it with the new way `select` is suppose to work.

df <- tibble(a = 1:5, b = 6:10)
var1 <- "a"

either of  this works fine:

df %>% select(a)
df %>% select_(var1)

and this doesn't work:

df %>% select(var1) # I knew this already would not work

# Error: var1: must resolve to integer column positions, not string

df %>% select(!!var1)

# Error: "a": must resolve to integer column positions, not string

df %>% select(UQ(var1))

# Error: "a": must resolve to integer column positions, not string

Honestly, I'm still struggling a little in wrapping my head around standard and non standard evaluation.

What is the proper approach to solve this issue?

Thanks in advance!

Massimo

[Hadley Wickham]

You've got two options:

1. Convert the string to a symbol:

df %>% select(!!sym(var1))

1. Use the existing one_of() helper

df %>% select(one_of(var))

Hadley

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