Bash: 计算关联数组中的键总数？

Question

考虑下面的关联数组：

declare -A shapingTimes
 shapingTimes=([0-start]=15 [0-stop]=21 [0-anotherkey]=foo)
shapingTimes+=([1-start]=4  [1-stop]=6  [1-anotherkey]=bar)
shapingTimes+=([2-start]=9  [2-stop]=11 [2-anotherkey]=blah)

有没有办法找到数组中每个条目使用的键总数？（这是数组中的每个 'index' 吗？）

例如，如何统计：[start]、[stop]、[anotherkey] = 3个键？

目前我正在使用我发现的这段代码中的硬编码值 (3)（如下所示），它可以很好地完成工作，但我想知道这是否可以动态实现？

totalshapingTimes=$((${#shapingTimes[*]} / 3))

我发现这些变量 return 数组的各个方面，但不是 键的总数 。

echo "All of the items in the array:" ${shapingTimes[*]}
echo "All of the indexes in the array:" ${!shapingTimes[*]}
echo "Total number of items in the array:" ${#shapingTimes[*]}
echo "Total number of KEYS in each array entry:" #???

期望输出：

All of the items in the array: 21 6 11 blah 15 4 bar 9 foo
All of the indexes in the array: 0-stop 1-stop 2-stop 2-anotherkey 0-start 1-start 1-anotherkey 2-start 0-anotherkey
Total number of items in the array: 9
Total number of KEYS in each array entry: 3

Answer 1

declare -A shapingTimes
shapingTimes=([0-start]=15 [0-stop]=21 [0-anotherkey]=foo)
shapingTimes+=([1-start]=4  [1-stop]=6  [1-anotherkey]=bar)
shapingTimes+=([2-start]=9  [2-stop]=11 [2-anotherkey]=blah)

# output all keys
for i in "${!shapingTimes[@]}"; do echo $i; done

输出：

1-start
2-stop
1-stop
0-start
2-start
2-anotherkey
1-anotherkey
0-stop
0-anotherkey

# Leading numbers and "-" removed:
for i in "${!shapingTimes[@]}"; do echo ${i/#[0-9]*-/}; done

输出：

start
stop
stop
start
start
anotherkey
anotherkey
stop
anotherkey

# put shortend keys in new associative array
declare -A hash
for i in "${!shapingTimes[@]}"; do hash[${i/#[0-9]*-/}]=""; done
echo "${#hash[@]}"

输出：

Answer 2

一旦您使用 - 键入您的数组名称，就没有直接的方法来识别超过 - 字符的字符串的出现次数。

一种方法是使用其他工具来确定计数。 "${!shapingTimes[@]}" 打印数组的所有键，sort -ut- k2 根据 - 定界符后的 2^nd 字段进行唯一排序，即通过管道传输到 wc -l 以获取行数。

printf '%s\n' "${!shapingTimes[@]}" | sort -ut- -k2 | wc -l
3

Answer 3

与相同，但没有循环也没有sub-shell:

#!/usr/bin/env bash

declare -A shapingTimes=(
  [0-start]=15 [0-stop]=21 [0-anotherkey]=foo
  [1-start]=4  [1-stop]=6  [1-anotherkey]=bar
  [2-start]=9  [2-stop]=11 [2-anotherkey]=blah
)

# Populate simple array with keys only
declare -a shapingTimesKeys=("${!shapingTimes[@]}")

# Create associative array entries declaration string
# populated by prefix stripped keys
printf -v _str '[%q]= ' "${shapingTimesKeys[@]/#[0-9]*-/}"

# Declare the stripped keys associative array using
# the string populated just above
declare -A shapingTimesHash="($_str)"

printf 'Found %d keys:\n' "${#shapingTimesHash[@]}"
printf '%q\n' "${!shapingTimesHash[@]}"

Bash: 计算关联数组中的键总数？

Bash: Count total number of keys in an associative array?

arrays

bash

associative-array