r-如何通过组合单个叶径来计算树的结果

Question

假设我有一个输入文件，其中每一行都包含从根（A）到叶的路径

echo "AtBtCnAtBtDnAtE" > lines.txt
A   B   C
A   B   D
A   E

如何轻松生成结果树？：(A(B(C,D),E))

我想使用GNU工具（awk、sed等），因为它们往往能更好地处理大文件，但R脚本也能工作。R输入为：

# lines <- lapply(readLines("lines.txt"), strsplit, " +")
lines <- list(list(c("A", "B", "C")), list(c("A", "B", "D")), list(c("A","E")))

Answer 1

在Perl中：

#!/usr/bin/env perl
use strict;
my $t = {};
while (<>) {
    my @a = split;
    my $t1 = $t;
    while (my $a = shift @a) {
        $t1->{$a} = {} if not exists $t1->{$a};
        $t1 = $t1->{$a};
    }
}
print &p($t)."n";
sub p {
    my ($t) = @_;
    return
    unless keys %$t;
    return '('
        . join(',', map { $_ . p($t->{$_}) } sort keys %$t)
        . ')';
}

此脚本返回：

% cat <<EOF | perl l.pl
A   B   C
A   B   D
A   E
EOF
(A(B(C,D),E))

请注意，由于p中的递归，该脚本根本不适合大型数据集。但这可以很容易地解决，把它变成一个双for循环，就像上面的第一个循环一样。

Answer 2

如果可以使用Bourne Shell脚本，为什么要用简单的方法呢？注意，这甚至不是Bash，这是一个普通的老式Bourne shell，没有数组。。。

#!/bin/sh
#
# A B C
# A B D
# A E
#
# "" vs "A B C"         -> 0->3, ident 0        -> -0+3 -> "(A(B(C"
# "A B C" vs "A B D"    -> 3->3, ident 2        -> -1+1 -> ",D"
# "A B D" vs "A E"      -> 3->2, ident 1        -> -2+1 -> "),E"
# "A E" vs. endc        -> 2->0, ident 0        -> -2+0 -> "))"
#
# Result: (A(B(C,D),E))
#
# Input stream is a path per line, path segments separated with spaces.
process_line () {
    local line2="$@"
    n2=$#
    set -- $line1
    n1=$#
    s=
    if [ $n2 = 0 ]; then                # last line (empty)
        for s1 in $line1; do
            s="$s)"
        done
    else
        sep=
        remainder=false
        for s2 in $line2; do
            if ! $remainder; then
                if [ "$1" != $s2 ]; then
                    remainder=true
                    if [ $# = 0 ]; then # only children
                        sep='('
                    else                # sibling to an existing element
                        sep=,
                        shift
                        for s1 in $@; do
                            s="$s)"
                        done
                    fi
                fi
            fi
            if $remainder; then         # Process remainder as mismatch
                s="$s$sep$s2"
                sep='('
            fi
            shift                       # remove the first element of line1
        done
    fi
    result="$result$s"
}
result=
line1=
(
    cat - 
    | sed -e 's/[[:space:]]+/ /' 
    | sed -e '/^$/d' 
    | sort -u
    echo ''                             # last line marker
) | while read line2; do
        process_line $line2
        line1="$line2"

        test -n "$line2" 
            || echo $result
    done

这为两个不同的文件生成了正确的答案（l.sh是shell版本，l.pl是Perl版本）：

% for i in l l1; do cat $i; ./l.sh < $i; ./l.pl < $i; echo; done
A
A B
A B C D
A B E F
A G H
A G H I
(A(B(C(D),E(F)),G(H(I))))
(A(B(C(D),E(F)),G(H(I))))
A B C
A B D
A E
(A(B(C,D),E))
(A(B(C,D),E))

哈哈！

Answer 3

好的，所以我想我得到了：

# input
lines <- c(list(c("A", "B", "C")), list(c("A", "B", "D")), list(c("A","E")))
# generate children
generate_children <- function(lines){
    children <- list()
    for (line in lines) {
        for (index in 1:(length(line)-1)){
            parent <- line[index]
            next_child <- line[index + 1]
            if (is.null(children[[parent]])){
                children[[parent]] <- next_child
            } else {
                if (next_child %notin% children[[parent]]){
                    children[[parent]] <- c(children[[parent]], next_child)
                }
            }
        }
    }
    children
}
expand_children <- function(current_parent, children){
    if (current_parent %in% names(children)){
        expanded_children <- sapply(children[[current_parent]], function(current_child){
            expand_children(current_child, children)
        }, USE.NAMES = FALSE)
        output <- setNames(list(expanded_children), current_parent)
    } else {
        output <- current_parent
    }
    output
}
children <- generate_children(lines)
root <- names(children)[1]
tree <- expand_children(root, children)
dput(tree)
# structure(list(A = structure(list(B = c("C", "D"), "E"), .Names = c("B",""))), .Names = "A")

有更简单的答案吗？