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(This article was first published on <strong><a href="https://scottishsnow.wordpress.com/2017/04/04/col-classes/"> R – scottishsnow</a></strong>, and kindly contributed to <a rel="nofollow" href="https://www.r-bloggers.com/">R-bloggers)</a> </div>
<p>When you write an ESRI Shapefile from R, writeOGR <a target="_blank" rel="nofollow" href="http://stackoverflow.com/a/36621487/2773500">assumes your numeric fields are real numbers</a> and so you get a lot of redundant zeros appended. This is misleading and distracting when you present data to third parties. You can fix this by changing column class from numeric to integer:</p>
<pre>
class(df$col) = &quot;integer&quot;
</pre>
<p>However, this only changes one column at a time. You can’t change the whole data frame (S4 spatial, or whatever) using the same method, or you’ll no longer have a data frame. Usually I’d solve this problem using an *apply method, in this case mapply or apply, but these don’t work in this case because <a target="_blank" rel="nofollow" href="http://grokbase.com/t/r/r-help/08817pnjxn/r-is-this-a-bug-apply-and-class/oldest">the data frame is coerced into a matrix</a>. This is one of the rare occasions when you need to use a for loop in R:</p>
<pre>
cols_to_change = c(1, 3, 5:9)
for(i in cols_to_change){
   class(df[, i]) = &quot;integer&quot;
}
</pre>
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