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    <p>Let's walk through what you did here.</p> <pre><code>data=c(0.6666667, 0.8333, 0.6666667, 0.8333, 0.8333, 0.75, 0.9999, 0.7499667, 0.25, 0.6666667, 0.1667, 0.7499667, 0.5, 0.2500333, 0.3333667, 0.0834, 0.0001, 0.2500333, 0.8333, 0.9999, 0.9999, 0.2500333, 0.2500333, 0.3333667, 0.9166, 0.5, 0.2500333, 0.4166667, 0.0001, 0.1667333, 0.6666333, 0.0834, 0.1667, 0.6666333, 0.9166, 0.1667, 0.7499333, 0.9166, 0.9166, 0.9166, 0.7499667, 0.7499667, 0.4166667, 0.5, 0.2500333, 0.9166, 0.6666667, 0.1667333, 0.25, 0.0001, 0.3333667, 0.0001, 0.25, 0.0834, 0.9999, 0.0834, 0.1667, 0.5, 0.2500333, 0.3333667, 0.9166, 0.9166, 0.8333, 0.9166, 0.75, 0.0834, 0.4166667, 0.5, 0.0001, 0.9999, 0.8333, 0.6666667, 0.9166) data_med=median(data) ## 0.5 quant_data=data ## irrelevant quant_data[quant_data&gt;data_med]="High" </code></pre> <p>But by doing this <strong>you have converted quant_data to a character vector</strong>:</p> <pre><code>str(quant_data) ## chr [1:73] "High" "High" "High" "High" "High" "High" "High" ... </code></pre> <p>Now the comparison between a character value and the <code>data_med</code> value is almost meaningless, because <code>data_med</code> will get coerced to a character value too:</p> <pre><code>"High" &lt; "0.5" ## FALSE "1e-4" &lt; "0.5" ## FALSE -- this is your problem. quant_data[quant_data&lt;=data_med]="Low" </code></pre> <p>What you presumably <em>meant</em> to do (and a reason to assign <code>quant_data=data</code>) was:</p> <pre><code>quant_data[data&gt;data_med]="High" quant_data[data&lt;=data_med]="Low" table(quant_data) ## High Low ## 35 38 </code></pre> <p>As @Arun points out in comments above, <code>quant_data &lt;- ifelse(data&gt;data_med,"High","Low")</code> would work too. So would an appropriate use of <code>cut()</code>.</p>
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    1. USBen Bolker
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    1. COActually, `quant_data<=data_med` works mostly. `"0.1" < 1` gives `TRUE`, but `"1e-4" < 1` gives false. So in the former the character is converted to numeric successfully, but it doesn't work with scientific format.
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      1. USRoland
    2. COIt's *not* converted to numeric, it's just that lexicographic sorting (see my comment above) happens to give you the right answer.
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    3. COAhh, I see. Thanks.
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