title: Using pmax/pmin with vector of variable string names in R
body: <p>Is there a way to use pmax and pmin function in R with a vector of string variable names using the tidyverse (dplyr) format?</p>
  <p>For instance,
  I want to run the following:</p>
  <pre><code>data(mtcars)
  mtcars %&gt;% mutate(maxval = pmax(drat, wt, na.rm = T)
  </code></pre>
  <p>This properly gets me the following:</p>
  <pre><code>                     mpg cyl  disp  hp drat    wt  qsec vs am gear carb maxval
  Mazda RX4           21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4  3.900
  Mazda RX4 Wag       21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4  3.900
  Datsun 710          22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1  3.850
  Hornet 4 Drive      21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1  3.215
  Hornet Sportabout   18.7   8 360.0 175 3.15 3.440 17.02  0  0    3    2  3.440
  Valiant             18.1   6 225.0 105 2.76 3.460 20.22  1  0    3    1  3.460
  Duster 360          14.3   8 360.0 245 3.21 3.570 15.84  0  0    3    4  3.570
  Merc 240D           24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2  3.690
  Merc 230            22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2  3.920
  Merc 280            19.2   6 167.6 123 3.92 3.440 18.30  1  0    4    4  3.920
  Merc 280C           17.8   6 167.6 123 3.92 3.440 18.90  1  0    4    4  3.920
  Merc 450SE          16.4   8 275.8 180 3.07 4.070 17.40  0  0    3    3  4.070
  Merc 450SL          17.3   8 275.8 180 3.07 3.730 17.60  0  0    3    3  3.730
  Merc 450SLC         15.2   8 275.8 180 3.07 3.780 18.00  0  0    3    3  3.780
  Cadillac Fleetwood  10.4   8 472.0 205 2.93 5.250 17.98  0  0    3    4  5.250
  Lincoln Continental 10.4   8 460.0 215 3.00 5.424 17.82  0  0    3    4  5.424
  Chrysler Imperial   14.7   8 440.0 230 3.23 5.345 17.42  0  0    3    4  5.345
  Fiat 128            32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1  4.080
  </code></pre>
  <p>But, say that I'm working on a very large data with quite a lot of variables, and I want to just use a vector of strings like <code>x1 = sprintf(&quot;xval_%1.0f&quot;, 1:25)</code> where x1 will be the list of variable columns I want to run pmax and pmin with. But when I do this, then I'm always given an error message that confuses the number of vectors with the number of observations. For instance, say I run the following:</p>
  <pre><code>values = c(&quot;drat&quot;, &quot;wt&quot;)
  mtcars %&gt;% mutate(maxval = pmax(all_of(values), na.rm = T))
  </code></pre>
  <p>Then I get the following error:</p>
  <pre><code>Error: Problem with `mutate()` column `maxval`.
  i `maxval = pmax(values, na.rm = T)`.
  i `maxval` must be size 32 or 1, not 2.
  </code></pre>
  <p>Which seems to be getting at the number of observations (32).</p>