delcols#

Purpose#

Returns a matrix with specified columns removed.

Format#

x_trim = delcols(x, c_idx)#
Parameters:

  • x (Matrix or dataframe)

  • c_idx (Scalar, string or vector) – index of columns to remove from x. These may be integers or variable names of a dataframe. Negative integers will start from the back. For example, -1 will indicate to remove the final column of x.

Returns:

x_trim (matrix) – equal to input x without columns specified by input c_idx. If no columns remain, x_trim will be an empty matrix.

Examples#

Example 1: Basic matrix usage#

x = { 1  2  3  4,
      5  6  7  8,
      9 10 11 12 };

// Remove the second column of 'x'
x_trim = delcols(x, 2);

After the above code:

          1  3  4
x_trim =  5  7  8
          9 11 12

Example 2: Remove two columns from a matrix#

x = { 1  2  3  4,
      5  6  7  8,
      9 10 11 12 };

// Remove the second and fourth columns of 'x'
c_idx = { 2, 4 };

x_trim = delcols(x, c_idx);

After the above code:

          1  3
x_trim =  5  7
          9 11

Example 3: Negative index example#

x = { 1  2  3  4,
      5  6  7  8,
      9 10 11 12 };

// Remove the final column of 'x'
x_trim = delcols(x, -1);

After the above code:

          1  2  3
x_trim =  5  6  7
          9 10 11

Example 4: Dataframe#

// Load three variables into a dataframe
fname = getGAUSSHome("examples/detroit.dta");
detroit = loadd(fname, "ft_police + unemployment + hourly_earn");

// Print the first three observations
print detroit[1:3,.];

will return the following output:

ft_police     unemployment      hourly_earn
260.35000        11.000000        2.9800000
269.80000        7.0000000        3.0900000
272.04000        5.2000000        3.2300000

// Remove the variable 'ft_police'
detroit = delcols(detroit, "ft_police");

// Print the first three observations
// after removing the variable
print detroit[1:3,.];

unemployment      hourly_earn
   11.000000        2.9800000
   7.0000000        3.0900000
   5.2000000        3.2300000

See also

Functions delif(), delrows(), selif()

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