title: Filter_at selected columns with multiple str_detect patterns
body: <p>What i should do should be pretty easy, yet, the newcomer that I am, I spent way too much time on trying to achieve this. With this script I try to filter out ALL observations from a data frame that contain ANY of the mentioned patterns. </p>
  
  <p>The script is:</p>
  
  <pre><code>df1 &lt;- filter_at(df, vars(contains("Pair")), 
                   any_vars(str_detect(., pattern="quinoaquinoa|lupinelupine", negate=TRUE)))
  </code></pre>
  
  <p>I do not get any error when I run this, however nothing changes and the expressions are not taken out from the dataframe. As i understand these functions  i could also place a <code>!</code> in front of <code>str_detect</code> instead of the <code>negate=TRUE</code>, however neither works.</p>
  
  <p>Note, the data frame is actually larger (has columns other than those containing "Pair", and the patterns to filter out will always be different and are retrieved from another data frame.</p>
  
  <p>The data frame looks like:</p>
  
  <pre><code>str(df)
  
  'data.frame':   653 obs. of  6 variables:
   $ Pair_1: Factor w/ 7 levels "grasscloverleycamelina",..: 3 7 7 3 3 3 7 6 6 6 ...
   $ Pair_2: Factor w/ 20 levels "camelinacamelina",..: 10 6 6 8 8 10 6 8 8 10 ...
   $ Pair_3: Factor w/ 20 levels "camelinacamelina",..: 19 20 20 20 19 19 20 20 20 16 ...
   $ Pair_4: Factor w/ 23 levels "camelinacamelina",..: 9 8 8 8 9 9 4 1 1 5 ...
   $ Pair_5: Factor w/ 20 levels "camelinacamelina",..: 9 12 16 16 13 13 12 12 11 11 ...
   $ Pair_6: Factor w/ 20 levels "camelinacamelina",..: 20 13 9 17 20 20 5 7 8 8 ...
  </code></pre>
  
  <p><code>dput</code> dataframe:</p>
  
  <pre><code>structure(list(Pair_1 = structure(c(3L, 7L, 7L, 3L, 3L, 3L), .Label = c("grasscloverleycamelina", 
  "grasscloverleyquinoa", "lupinecamelina", "lupinegrasscloverley", 
  "lupinelupine", "lupinequinoa", "lupinespringcereal"), class = "factor"), 
      Pair_2 = structure(c(10L, 6L, 6L, 8L, 8L, 10L), .Label = c("camelinacamelina", 
      "camelinagrasscloverley", "camelinalupine", "camelinaquinoa", 
      "camelinaspringcereal", "grasscloverleycamelina", "grasscloverleygrasscloverley", 
      "grasscloverleylupine", "grasscloverleyquinoa", "grasscloverleyspringcereal", 
      "quinoacamelina", "quinoagrasscloverley", "quinoalupine", 
      "quinoaquinoa", "quinoaspringcereal", "springcerealcamelina", 
      "springcerealgrasscloverley", "springcereallupine", "springcerealquinoa", 
      "springcerealspringcereal"), class = "factor"), Pair_3 = structure(c(19L, 
      20L, 20L, 20L, 19L, 19L), .Label = c("camelinacamelina", 
      "camelinagrasscloverley", "camelinalupine", "camelinaquinoa", 
      "camelinaspringcereal", "grasscloverleycamelina", "grasscloverleygrasscloverley", 
      "grasscloverleylupine", "grasscloverleyquinoa", "grasscloverleyspringcereal", 
      "quinoacamelina", "quinoagrasscloverley", "quinoalupine", 
      "quinoaquinoa", "quinoaspringcereal", "springcerealcamelina", 
      "springcerealgrasscloverley", "springcereallupine", "springcerealquinoa", 
      "springcerealspringcereal"), class = "factor"), Pair_4 = structure(c(9L, 
      8L, 8L, 8L, 9L, 9L), .Label = c("camelinacamelina", "camelinagrasscloverley", 
      "camelinalupine", "camelinaquinoa", "camelinaspringcereal", 
      "grasscloverleycamelina", "grasscloverleygrasscloverley", 
      "grasscloverleyquinoa", "grasscloverleyspringcereal", "lupinecamelina", 
      "lupinegrasscloverley", "lupinelupine", "lupinequinoa", "lupinespringcereal", 
      "quinoacamelina", "quinoagrasscloverley", "quinoaquinoa", 
      "quinoaspringcereal", "springcerealcamelina", "springcerealgrasscloverley", 
      "springcereallupine", "springcerealquinoa", "springcerealspringcereal"
      ), class = "factor"), Pair_5 = structure(c(9L, 12L, 16L, 
      16L, 13L, 13L), .Label = c("camelinacamelina", "camelinagrasscloverley", 
      "camelinaquinoa", "camelinaspringcereal", "grasscloverleycamelina", 
      "grasscloverleygrasscloverley", "grasscloverleyquinoa", "grasscloverleyspringcereal", 
      "lupinecamelina", "lupinegrasscloverley", "lupinequinoa", 
      "lupinespringcereal", "quinoacamelina", "quinoagrasscloverley", 
      "quinoaquinoa", "quinoaspringcereal", "springcerealcamelina", 
      "springcerealgrasscloverley", "springcerealquinoa", "springcerealspringcereal"
      ), class = "factor"), Pair_6 = structure(c(20L, 13L, 9L, 
      17L, 20L, 20L), .Label = c("camelinacamelina", "camelinagrasscloverley", 
      "camelinaquinoa", "camelinaspringcereal", "grasscloverleycamelina", 
      "grasscloverleygrasscloverley", "grasscloverleyquinoa", "grasscloverleyspringcereal", 
      "lupinecamelina", "lupinegrasscloverley", "lupinequinoa", 
      "lupinespringcereal", "quinoacamelina", "quinoagrasscloverley", 
      "quinoaquinoa", "quinoaspringcereal", "springcerealcamelina", 
      "springcerealgrasscloverley", "springcerealquinoa", "springcerealspringcereal"
      ), class = "factor")), row.names = c(NA, 6L), class = "data.frame")
  </code></pre>