find lowest value and index of floating point array awk, sed, sort - sorting

Question

I have the following array:
echo $array
0.3 0.3 0.4 0.4 0.4 0.4 0.4 0.4 0.3 0.3 0.2 0.4 0.4 0.4 0.4 0.5 0.5 0.4 0.2
I have written a code to sort the values and also get the index number:
echo $array | tr -s ' ' '\n' | awk '{print($0" "NR)}' | sort -g -k1,1
0.2 11
0.2 19
0.3 1
0.3 10
0.3 2
0.3 9
0.4 12
0.4 13
0.4 14
0.4 15
0.4 18
0.4 3
0.4 4
0.4 5
0.4 6
0.4 7
0.4 8
0.5 16
0.5 17
I am having a difficult time extracting only the rows which have the lowest value in the first column (i.e., the lowest values in the array, overall). For example, the desired final product for the above example would be:
0.2 11
0.2 19
It should be able to handle instances of one, and multiple lowest value indices. The code does not need to include any sort of awk, sort, sed, or any commands if they do not need to - anything could work (this is just as far as I have gotten with achieving the final task).

Answer 1

Print the output until the number in the first column does not change.
echo $array | tr -s ' ' '\n' | awk '{print($0" "NR)}' | sort -g -k1,1 |
awk 'length(last) == 0 || last == $1 { last=$1; print; }'
Notes:
It's best to always quote variable expansions echo "$array".
If you don't quote $array, you could just printf "%s\n" $array
You could use nl to number lines (but the columns order would be different).

Answer 2

Using asort() funtion in awk
awk '{split($0,a); for (i in a) a[i]=a[i]" "i; n=asort(a); for (i = 1; i <= 2; i++) print a[i]} '
Demo:
$echo $array
0.3 0.3 0.4 0.4 0.4 0.4 0.4 0.4 0.3 0.3 0.2 0.4 0.4 0.4 0.4 0.5 0.5 0.4 0.2
$echo $array | awk '{split($0,a); for (i in a) a[i]=a[i]" "i; n=asort(a); for (i = 1; i <= 2; i++) print a[i]} '
0.2 11
0.2 19
$
Explanation:
{split($0,a); -- Initialize a array a from input record
for (i in a) a[i]=a[i]" "i; -- Append current row number to existing value
n=asort(a); -- Call sort array function and store number of element in variable n.
for (i = 1; i <= 2; i++) -- loop for first 2 element of array
print a[i]}
Documentation on asort()
P.S. --> storing number of element in n was not required.