Is there a quick way to transform column data type?

[#1]

I have a question for help, thanks.
There is a table with more than 1200 columns, since many data values starting with “i”, there are about 900 columns, so I need to convert the column format from character to numeric, but with a for loop, it's too slow, is there a fast way?

[#2]

For clarification, when you state 'many data values starting with “i”', you are saying that within a column you have data values such as

     i78

?

If this is what you are referring to, dose the value need to be changed to 

     178

or just remove the "i" and leave

     78

or just set the value to a missing value

[#3]

There are many values starting with i, we define these datas  as invalid values anyway, must be turned into missing values

[#4]

You could try selecting the columns, right clicking and using 

[#5]

For Each( {col, index}, {:a, :b, :c},
		col << Data Type( numeric ) << 
		Set Modeling Type( "continuous" )
	);

Thanks!  But it is still slowly when there are thousand columns with many values.

[#6]

You can try to speed it up by making your data table invisible (open it as invisible/query it as invisible or use << show window(0)) and using << Begin Data Update before and << End Data Update after your loop.

[#7]

col_names=dt<<get column names(string);
st=hptime();
dt<<Begin Data Update;

for each({col,index},col_names,
	column(dt,col)<<data type(numeric)<<set modeling type(continuous)
);

dt << End Data Update;
en=hptime();
show(en-st)

Thanks!  It's still slow, 20minutes...

Is there a way to change the format before data importing?

[#8]

Maybe (I don't think you have defined where the data is coming from at all)? In best case you can fix your data at the source