Search values across all columns in R data frame
<p>Here's a sample data frame. </p>

<pre><code>df = data.frame(company = c('a', 'b', 'c', 'd'),
                 bond = c(0.2, 1, 0.3, 0),
                 equity = c(0.7, 0, 0.5, 1),
                 cash = c(0.1, 0, 0.2, 0))
df

  company bond equity cash
1       a  0.2    0.7  0.1
2       b  1.0    0.0  0.0
3       c  0.3    0.5  0.2
4       d  0.0    1.0  0.0
</code></pre>

<p>I need to find companies which have 1.0 in any columns. 
The expected result should be <strong>b and d</strong>.</p>

<p>Please provide a solution that works for >20 columns. 
Solutions like <code>df %&gt;% filter(bond == 1)</code> only works for searching a particular column.</p>

<p><code>dplyr</code> or <code>data.table</code> solutions are acceptable.</p>

<p>Thanks.</p>