lsearch - See if a list contains a particular element
lsearch ?
options?
list pattern
This command searches the elements of
list to see if one of them matches
pattern. If so, the command returns the index of the first matching
element (unless the options
-all or
-inline are specified.) If
not, the command returns
-1 or (if options
-all or
-inline are specified) the empty string. The
option arguments
indicates how the elements of the list are to be matched against
pattern and must have one of the values below:
If all matching style options are omitted, the default matching style is
-glob. If more than one matching style is specified, the last matching
style given takes precedence.
- -exact
-
Pattern is a literal string that is compared for
exact equality against each list element.
- -glob
-
Pattern is a glob-style pattern which is matched
against each list element using the same rules as the string match
command.
- -regexp
-
Pattern is treated as a regular expression and
matched against each list element using the rules described in the
re_syntax reference page.
- -sorted
- The list elements are in sorted order. If this option is
specified, lsearch will use a more efficient searching algorithm to
search list. If no other options are specified, list is
assumed to be sorted in increasing order, and to contain ASCII strings.
This option is mutually exclusive with -glob and -regexp,
and is treated exactly like -exact when either -all or
-not are specified.
These options may be given with all matching styles.
- -all
- Changes the result to be the list of all matching indices
(or all matching values if -inline is specified as well.) If
indices are returned, the indices will be in numeric order. If values are
returned, the order of the values will be the order of those values within
the input list.
- -inline
- The matching value is returned instead of its index (or an
empty string if no value matches.) If -all is also specified, then
the result of the command is the list of all values that matched.
- -not
- This negates the sense of the match, returning the index of
the first non-matching value in the list.
-
-start index
- The list is searched starting at position index. The
interpretation of the index value is the same as for the command
string index, supporting simple index arithmetic and indices
relative to the end of the list.
These options describe how to interpret the items in the list being searched.
They are only meaningful when used with the
-exact and
-sorted
options. If more than one is specified, the last one takes precedence. The
default is
-ascii.
- -ascii
- The list elements are to be examined as Unicode strings
(the name is for backward-compatibility reasons.)
- -dictionary
- The list elements are to be compared using dictionary-style
comparisons (see lsort for a fuller description). Note that this
only makes a meaningful difference from the -ascii option when the
-sorted option is given, because values are only dictionary-equal
when exactly equal.
- -integer
- The list elements are to be compared as integers.
- -nocase
- Causes comparisons to be handled in a case-insensitive
manner. Has no effect if combined with the -dictionary,
-integer, or -real options.
- -real
- The list elements are to be compared as floating-point
values.
These options (only meaningful with the
-sorted option) specify how the
list is sorted. If more than one is given, the last one takes precedence. The
default option is
-increasing.
- -decreasing
- The list elements are sorted in decreasing order. This
option is only meaningful when used with -sorted.
- -increasing
- The list elements are sorted in increasing order. This
option is only meaningful when used with -sorted.
- -bisect
- Inexact search when the list elements are in sorted order.
For an increasing list the last index where the element is less than or
equal to the pattern is returned. For a decreasing list the last index
where the element is greater than or equal to the pattern is returned. If
the pattern is before the first element or the list is empty, -1 is
returned. This option implies -sorted and cannot be used with
either -all or -not.
These options are used to search lists of lists. They may be used with any other
options.
-
-index indexList
- This option is designed for use when searching within
nested lists. The indexList argument gives a path of indices (much
as might be used with the lindex or lset commands) within
each element to allow the location of the term being matched against.
- -subindices
- If this option is given, the index result from this command
(or every index result when -all is also specified) will be a
complete path (suitable for use with lindex or lset) within
the overall list to the term found. This option has no effect unless the
-index is also specified, and is just a convenience short-cut.
Basic searching:
lsearch {a b c d e} c
→ 2
lsearch -all {a b c a b c} c
→ 2 5
Using
lsearch to filter lists:
lsearch -inline {a20 b35 c47} b*
→ b35
lsearch -inline -not {a20 b35 c47} b*
→ a20
lsearch -all -inline -not {a20 b35 c47} b*
→ a20 c47
lsearch -all -not {a20 b35 c47} b*
→ 0 2
This can even do a “set-like” removal operation:
lsearch -all -inline -not -exact {a b c a d e a f g a} a
→ b c d e f g
Searching may start part-way through the list:
lsearch -start 3 {a b c a b c} c
→ 5
It is also possible to search inside elements:
lsearch -index 1 -all -inline {{a abc} {b bcd} {c cde}} *bc*
→ {a abc} {b bcd}
foreach(3tcl),
list(3tcl),
lappend(3tcl),
lindex(3tcl),
linsert(3tcl),
llength(3tcl),
lset(3tcl),
lsort(3tcl),
lrange(3tcl),
lreplace(3tcl),
string(3tcl)
binary search, linear search, list, match, pattern, regular expression, search,
string