title: Remove whitespace in string using for loop
body: <p>I learned about stringr library and tried to use it to remove whitespace from a string, but I don't understand why it would not remove it when I index a string from a vector.</p>
  
  <p><code>ex</code> is a vector with strings similar to <code>"  1950"</code></p>
  
  <pre><code>&gt; library(stringr)
  &gt; str_replace_all(ex[1], fixed("  "), "")
  [1] "  1950"
  &gt; str_replace_all("  1950", fixed("  "), "")
  [1] "1950"
  &gt; str("  1950")
   chr "  1950"
  &gt; str(ex[1])
   chr "  1950"
  </code></pre>
  
  <p>I wanted to write a loop to remove the whitespaces, but I don't understand why <code>stringr</code> does not work when I use <code>ex[1]</code></p>
  
  <p>Following is <code>dput(ex)</code></p>
  
  <pre><code>c("  1950", "  1951", "  1952", "  1953", "  1954", 
  "  1955", "  1956", "  1957", "  1958", "  1959", "  1960", 
  "  1961", "  1962", "  1963", "  1964", "  1965", "  1966", 
  "  1967", "  1968", "  1969", "  1970", "  1971", "  1972", 
  "  1973", "  1974", "  1975", "  1976", "  1977", "  1978", 
  "  1979", "  1980", "  1981", "  1982", "  1983", "  1984", 
  "  1985", "  1986", "  1987", "  1988", "  1989", "  1990", 
  "  1991", "  1992", "  1993", "  1994", "  1995", "  1996", 
  "  1997", "  1998", "  1999", "  2000", "  2001", "  2002", 
  "  2003", "  2004", "  2005", "  2006", "  2007", "  2008", 
  "  2009", "  2010", "  2011", "  2012", "  2013", "  2014", 
  "  2015", "  2016", "  2017", "        ", "Provided by :   All China Marketing Resarch"
  )
  </code></pre>
  
  <p>What library can I use in a for loop to remove whitespaces?</p>