Convert string elements in series to floats in Red language

Question

I want to convert many decimal numbers available as strings to floats in one go. I am trying following code which combines these strings into a series and then convert them to floats. This works all right but fails if there is an error:

a: "1.5" 
b: ""
c: "3.7"
invars: [a b c]

print a
print type? a

set invars foreach x invars [append [] to-float reduce x]  ; code to convert string series to float series; 

print a
print type? a

The error is:

*** Script Error: cannot MAKE/TO float! from: ""
*** Where: to
*** Stack: to-float 

For error correction, I tried following code:

temp: []
foreach x invars [
    y: copy ""
    either error? [set [y] to-float reduce x]
        [append temp reduce x]         ; put original value if not convertable
        [append temp reduce y]  ]
print temp 
set invars temp
print a 
print type? a

But this is also not working. Where is the problem and how can this be corrected?

Answer 1

forall invars [invars/1:  load get invars/1]
>> invars
== [1.5 [] 3.7]

and if you want to get rid of the empty blocks

>> replace/all invars block! 0
== [1.5 0 3.7]

and if you really want to do all in (:less:) steps

forall invars [invars/1: either empty? invars/1: get invars/1 [0.0] [load invars/1]]

After you can set your variables again.

But if you want just set your variables, you have to do

foreach x invars [set :x load get x]

with to-float

 foreach x invars [either empty? get x [set :x 0] [set :x to-float get x]]

and finally an all error safe version with to-float

foreach x invars [attempt [set :x to-float get x]]
== 3.7
>> a
== 1.5
>> b
== ""
>> c
== 3.7