EVOLUTION-MANAGER

Edit File: list.search.html

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><title>R: Search a list recusively by an expression</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link rel="stylesheet" type="text/css" href="R.css" />
</head><body>

<table width="100%" summary="page for list.search {rlist}"><tr><td>list.search {rlist}</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Search a list recusively by an expression</h2>

<h3>Description</h3>

<p>Search a list recusively by an expression
</p>

<h3>Usage</h3>

<pre>
list.search(.data, expr, classes = "ANY", n, unlist = FALSE)
</pre>

<h3>Arguments</h3>

<table summary="R argblock">
<tr valign="top"><td><code>.data</code></td>
<td>
<p>A <code>list</code> or <code>vector</code></p>
</td></tr>
<tr valign="top"><td><code>expr</code></td>
<td>
<p>a lambda expression</p>
</td></tr>
<tr valign="top"><td><code>classes</code></td>
<td>
<p>a character vector of class names that restrict the search.
By default, the range is unrestricted (<code>ANY</code>).</p>
</td></tr>
<tr valign="top"><td><code>n</code></td>
<td>
<p>the maximal number of vectors to return</p>
</td></tr>
<tr valign="top"><td><code>unlist</code></td>
<td>
<p><code>logical</code> Should the result be unlisted?</p>
</td></tr>
</table>

<h3>Details</h3>

<p><code>list.search</code> evaluates an expression (<code>expr</code>) recursively
along a list (<code>.data</code>).
</p>
<p>If the expression results in a single-valued logical vector and its
value is <code>TRUE</code>, the whole vector will be collected If it results
in multi-valued or non-logical vector, the non-<code>NA</code> values
resulted from the expression will be collected.
</p>
<p>To search whole vectors that meet certain condition, specify the
expression that returns a single logical value.
</p>
<p>To search the specific values within the vectors, use subsetting in the
expression, that is, <code>.[cond]</code> or lambda expression like
<code>x -&gt; x[cond]</code> where <code>cond</code> is a logical vector used to
select the elements in the vector.
</p>

<h3>Examples</h3>

<pre>
# Exact search

x &lt;- list(p1 = list(type='A',score=c(c1=9)),
       p2 = list(type=c('A','B'),score=c(c1=8,c2=9)),
       p3 = list(type=c('B','C'),score=c(c1=9,c2=7)),
       p4 = list(type=c('B','C'),score=c(c1=8,c2=NA)))

## Search exact values
list.search(x, identical(., 'A'))
list.search(x, identical(., c('A','B')))
list.search(x, identical(., c(9,7)))
list.search(x, identical(., c(c1=9,c2=7)))

## Search all equal values
list.search(x, all(. == 9))
list.search(x, all(. == c(8,9)))
list.search(x, all(. == c(8,9), na.rm = TRUE))

## Search any equal values
list.search(x, any(. == 9))
list.search(x, any(. == c(8,9)))

# Fuzzy search

data &lt;- list(
  p1 = list(name='Ken',age=24),
  p2 = list(name='Kent',age=26),
  p3 = list(name='Sam',age=24),
  p4 = list(name='Keynes',age=30),
  p5 = list(name='Kwen',age=31)
)

list.search(data, grepl('^K\\w+n$', .), 'character')

## Not run: 
library(stringdist)
list.search(data, stringdist(., 'Ken') &lt;= 1, 'character')
list.search(data, stringdist(., 'Man') &lt;= 2, 'character')
list.search(data, stringdist(., 'Man') &gt; 2, 'character')

## End(Not run)

data &lt;- list(
  p1 = list(name=c('Ken', 'Ren'),age=24),
  p2 = list(name=c('Kent', 'Potter'),age=26),
  p3 = list(name=c('Sam', 'Lee'),age=24),
  p4 = list(name=c('Keynes', 'Bond'),age=30),
  p5 = list(name=c('Kwen', 'Hu'),age=31))

list.search(data, .[grepl('e', .)], 'character')

## Not run: 
list.search(data, all(stringdist(., 'Ken') &lt;= 1), 'character')
list.search(data, any(stringdist(., 'Ken') &gt; 1), 'character')

## End(Not run)
</pre>

<hr /><div style="text-align: center;">[Package <em>rlist</em> version 0.4.6.2 <a href="00Index.html">Index</a>]</div>
</body></html>