在Bash中将索引数组转换为关联数组 [英] Convert an indexed array into an associative array in Bash

问题描述

目前，我正在努力寻找以下任一问题的解决方案:

At present, I’m struggling to find solution to either of the following problems:

1. 如何将普通数组(索引从0开始的索引数组)转换为关联数组，其中value成为键，而value本身就是值.
2. 从索引数组创建一个新的assoc数组，其中值是键.而这在一个声明中.我知道可以很好地使用循环来完成此操作，但是对于包含近500,000个元素的大型数组而言，循环是一项开销.

3. 根据mysql sql查询的结果创建一个assoc数组.我通常从mysql sql查询结果创建索引数组，如下所示:

1. how to convert a normal array (indexed array with index starting at 0) into an associative array where value becomes a key and value itself is the value.
2. Create a new assoc array from indexed array where values are keys. And this in a single statement. I know it can very well be done using a loop but for a huge sized array containing almost 500,000 elements, a loop is an overhead.

3. Create an assoc array from the result of mysql sql query. I normally create an indexed array from a mysql sql query result as below:

mapfile -t a_dummy <<< "$(mysql -u root –disable-column-names –silent -B -e "select * from dummy_tbl;" "$DB_NAME")"

其中$ DB_NAME是指向数据库名称字符串的变量.

where $DB_NAME is the variable pointing to DB name string.

推荐答案

这是使用sed的一种方法.请注意，这仅在原始数组的所有元素都不包含空格的情况下起作用.

Here's one way, using sed. Note that this will only work, however, if none of the elements of the original array contain whitespace.

declare -A "newArray=( $(echo ${oldArray[@]} | sed 's/[^ ]*/[&]=&/g') )"

sed命令采用每个数组元素"x"，并将其替换为字符串"[x] = x"，适用于关联数组分配.

The sed command takes each array element 'x' and replaces it with the string '[x]=x', suitable for an associative array assignment.

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