topic Re: Column formula referencing variable column names in Discussions

Column formula referencing variable column names

jeric — Sat, 01 Nov 2014 17:05:10 GMT

Greetings,

For analyzing electrical data I want to create new columns with an absolute value formula referring to other columns whose names may be different in different data sets but start with "ID" or "IG". When I apply below the formula for every new column is the absolute value using the last measurement column found, not the column corresponding to different measurement columns. How should I express that each "ABS" formula applies to the measurement column?

cdt = Current Data Table();

ColNames = {};

ColNames=cdt<< Get Column Names(string);

for (i=1, i<= N items(ColNames), i++,

if (Substr(ColNames ,1,2) == "ID" |

Substr(ColNames ,1,2)== "IG" ,

(

col = Column(i);

New Column("ABS " || ColNames , (Formula(Abs(As Column (col)))), format("Scientific", 6, 1));

Re: Column formula referencing variable column names

ian_jmp — Mon, 03 Nov 2014 21:02:39 GMT

NamesDefaultToHere(1);

// Make a table . . .

dt = NewTable("ETEST",

NewColumn("ID_1", Numeric, Continuous, Formula(RandomNormal())),

NewColumn("ID_2", Numeric, Continuous, Formula(RandomNormal())),

NewColumn("Not Required", Numeric, Continuous, Formula(RandomNormal())),

NewColumn("IG_1", Numeric, Continuous, Formula(RandomNormal())),

NewColumn("IG_2", Numeric, Continuous, Formula(RandomNormal())),

AddRows(10)

);

// Add new formula columns as required . . .

cols = dt << GetColumnNames("String");

Wait(3);

For(c=1, c<=NItems(cols), c++,

If(StartsWith(cols[c], "ID") | StartsWith(cols[c], "IG"),

// Template expression for adding the new column by a formula

CMD = Expr( dt << NewColumn("ABS("||cols[c]||")", Numeric, Continuous, Formula(Abs(colTBD))) );

// Update the expression with values for this iteration . . .

SubstituteInto(CMD, Expr(colTBD), AsName(cols[c]));

// Add the required column

CMD;

);

Re: Column formula referencing variable column names

jeric — Tue, 04 Nov 2014 00:21:16 GMT

Works like a charm. Thank you, sir!