dfaddcol#

Purpose#

Adds a new named column to a dataframe.

Format#

df_new = dfaddcol(df, name, data)#

Parameters:

df (NxK Dataframe) – The dataframe to add a column to.
name (String) – The name for the new column.
data (Nx1 vector, string array, or dataframe) – The data for the new column.

Returns:

df_new (Nx(K+1) Dataframe) – The original dataframe with the new column appended on the right.

Examples#

Add a computed column#

// Load dataset
fname = getGAUSSHome("examples/auto2.dta");
auto2 = loadd(fname);

// Add a new column computed from an existing column
auto2 = dfaddcol(auto2, "price_k", auto2[., "price"] ./ 1000);

// Preview first 5 rows of selected columns
head(auto2[., "make" "price" "price_k"]);

         make            price          price_k
  AMC Concord         4099.000         4.099000
    AMC Pacer         4749.000         4.749000
   AMC Spirit         3799.000         3.799000
Buick Century         4816.000         4.816000
Buick Electra         7827.000         7.827000

Add a string column#

// Create a small numeric dataframe
x = asdf(100 | 200 | 300, "value");

// Add a string column
x = dfaddcol(x, "label", "low" $| "mid" $| "high");

x =          value            label
         100.00000              low
         200.00000              mid
         300.00000             high

Remarks#

dfaddcol() always appends the new column to the right side of the dataframe. To insert a column at a specific position, use insertcols().
The data argument must have the same number of rows as df.
This function is equivalent to df ~ asDF(data, name) but reads more clearly when adding computed columns.