spA = {}; spB = {}; spC = {};
AppendTo[#, {"Up", "Down"}] & /@ {spA, spB, spC}
doesn't work in Mathematica 11.1.1.
Why? What is an alternative?
It's an evaluation leak issue. You could try:
spA={}; spB={}; spC={};
Function[Null,AppendTo[#,{"Up","Down"}],HoldAll] /@ Unevaluated@{spA,spB,spC};
spA
spB
spC
{{"Up", "Down"}}
{{"Up", "Down"}}
{{"Up", "Down"}}
a = b = c = {};
Using Append
with ApplyTo
(new in 12.2)
{a, b, c} //= Map @ First @* Append[{"Up", "Down"}];
{a, b, c}
{{"Up", "Down"}, {"Up", "Down"}, {"Up", "Down"}}
An alternative is to use Insert
:
a = b = c = {};
Flatten@Insert[{"Up", "Down"}, #, 1] & /@ {a, b, c}
(*{{"Up", "Down"}, {"Up", "Down"}, {"Up", "Down"}}*)
Append
? $\endgroup$