lsort(3tcl) | Tcl Built-In Commands | lsort(3tcl) |
lsort - Sort the elements of a list
lsort ?options? list
This command sorts the elements of list, returning a new list in sorted order. The implementation of the lsort command uses the merge-sort algorithm which is a stable sort that has O(n log n) performance characteristics.
By default ASCII sorting is used with the result returned in increasing order. However, any of the following options may be specified before list to control the sorting process (unique abbreviations are accepted):
lsort -integer -index 1 \
{{First 24} {Second 18} {Third 30}}
returns {Second 18} {First 24} {Third 30},
lsort -index end-1 \
{{a 1 e i} {b 2 3 f g} {c 4 5 6 d h}}
returns {c 4 5 6 d h} {a 1 e i} {b 2 3 f g}, and
lsort -index {0 1} {
{{b i g} 12345}
{{d e m o} 34512}
{{c o d e} 54321} }
returns {{d e m o} 34512} {{b i g} 12345} {{c o d e} 54321} (because e sorts before i which sorts before o.) This option is much more efficient than using -command to achieve the same effect.
The list length must be an integer multiple of strideLength, which in turn must be at least 2.
For example,
lsort -stride 2 {carrot 10 apple 50 banana 25}
returns “apple 50 banana 25 carrot 10”, and
lsort -stride 2 -index 1 -integer {carrot 10 apple 50 banana 25}
returns “carrot 10 banana 25 apple 50”.
The options to lsort only control what sort of comparison is used, and do not necessarily constrain what the values themselves actually are. This distinction is only noticeable when the list to be sorted has fewer than two elements.
The lsort command is reentrant, meaning it is safe to use as part of the implementation of a command used in the -command option.
Sorting a list using ASCII sorting:
% lsort {a10 B2 b1 a1 a2} B2 a1 a10 a2 b1
Sorting a list using Dictionary sorting:
% lsort -dictionary {a10 B2 b1 a1 a2} a1 a2 a10 b1 B2
Sorting lists of integers:
% lsort -integer {5 3 1 2 11 4} 1 2 3 4 5 11 % lsort -integer {1 2 0x5 7 0 4 -1} -1 0 1 2 4 0x5 7
Sorting lists of floating-point numbers:
% lsort -real {5 3 1 2 11 4} 1 2 3 4 5 11 % lsort -real {.5 0.07e1 0.4 6e-1} 0.4 .5 6e-1 0.07e1
Sorting using indices:
% # Note the space character before the c % lsort {{a 5} { c 3} {b 4} {e 1} {d 2}} { c 3} {a 5} {b 4} {d 2} {e 1} % lsort -index 0 {{a 5} { c 3} {b 4} {e 1} {d 2}} {a 5} {b 4} { c 3} {d 2} {e 1} % lsort -index 1 {{a 5} { c 3} {b 4} {e 1} {d 2}} {e 1} {d 2} { c 3} {b 4} {a 5}
Sorting a dictionary:
% set d [dict create c d a b h i f g c e] c e a b h i f g % lsort -stride 2 $d a b c e f g h i
Sorting using striding and multiple indices:
% # Note the first index value is relative to the group % lsort -stride 3 -index {0 1} \
{{Bob Smith} 25 Audi {Jane Doe} 40 Ford} {{Jane Doe} 40 Ford {Bob Smith} 25 Audi}
Stripping duplicate values using sorting:
% lsort -unique {a b c a b c a b c} a b c
More complex sorting using a comparison function:
% proc compare {a b} {
set a0 [lindex $a 0]
set b0 [lindex $b 0]
if {$a0 < $b0} {
return -1
} elseif {$a0 > $b0} {
return 1
}
return [string compare [lindex $a 1] [lindex $b 1]] } % lsort -command compare \
{{3 apple} {0x2 carrot} {1 dingo} {2 banana}} {1 dingo} {2 banana} {0x2 carrot} {3 apple}
list(3tcl), lappend(3tcl), lindex(3tcl), linsert(3tcl), llength(3tcl), lsearch(3tcl), lset(3tcl), lrange(3tcl), lreplace(3tcl)
element, list, order, sort
8.5 | Tcl |