LINE Subcommand (IGRAPH command)

LINE creates line charts, dot charts, and ribbon charts. These charts summarize categories of one or more variables. Line charts tend to emphasize flow or movement instead of individual values. They are commonly used to display data over time and therefore can be used to give a good sense of trends. A ribbon chart is similar to a line chart, with the lines displayed as ribbons in a third dimension. Ribbon charts can either have two dimensions displayed with a 3-D effect, or they can have three dimensions.

The following keywords are available:

summary function. Defines a function used to summarize the variable defined on the Y subcommand. If the Y axis assignment is $COUNT or $PCT, the LINE subcommand cannot have a summary function. If the Y subcommand specifies TYPE=CATEGORICAL, then LINE can specify only MODE as the summary function.

STYLE. Chart can include dots and lines ( DOTLINE ), lines only ( LINE ), or dots only ( DOT ). The keyword NONE creates an empty chart.

DROPLINE. Indicates whether drop lines through points having the same value of a variable are included in the chart ( ON ) or not ( OFF ). To include drop lines, specify a categorical variable on the STYLE, COLOR, or SIZE subcommands.

LABEL. Labels points with the actual values corresponding to the dependent axis ( VAL ), the percentage of cases ( PCT ), and the number of cases included in each data point ( N ). The default is no labels.

LINELABEL. Labels lines with category labels ( CAT ), the percentage of cases ( PCT ), and the number of cases included in each line ( N ). The default is no labels.

BREAK. Indicates whether the lines break at missing values ( MISSING ) or not ( NONE ).

The INTERPOLATE keyword determines how the lines connecting the points are drawn. Options include:

STRAIGHT. Straight lines.

LSTEP. A horizontal line extends from each data point. A vertical riser connects the line to the next data point.

CSTEP. Each data point is centered on a horizontal line that extends half of the distance between consecutive points. Vertical risers connect the line to the next horizontal line.

RSTEP. A horizontal line terminates at each data point. A vertical riser extends from each data point, connecting to the next horizontal line.

LJUMP. A horizontal line extends from each data point. No vertical risers connect the lines to the points.

RJUMP. A horizontal line terminates at each data point. No vertical risers connect the points to the next horizontal line.

CJUMP. A horizontal line is centered at each data point, extending half of the distance between consecutive points. No vertical risers connect the lines.

SPLINE. Connects data points with a cubic spline.

LAGRANGE3. This is no longer supported and is now an alias for SPLINE.

LAGRANGE5. This is no longer supported and is now an alias for SPLINE.

Example

IGRAPH
 /X1=VAR(volume95) TYPE=CATEGORICAL
 /Y=VAR(sales96) TYPE=SCALE
 /COLOR=VAR(volume94) TYPE=CATEGORICAL
 /COORDINATE=VERTICAL
 /LINE (MEAN) STYLE=LINE DROPLINE=ON LABEL VAL
 INTERPOLATE=STRAIGHT BREAK=MISSING.
  • LINE creates a line chart. The lines represent the mean value of sales96 for each category of volume95.
  • The chart contains a line for each category of volume94, with droplines connecting the lines at each category of volume95.
  • LABEL labels the lines with the mean sales96 value for each category of volume95.
  • INTERPOLATE specifies that straight lines connect the mean sales96 values across the volume95 categories.
  • BREAK indicates that the lines will break at any missing values.