class pyqtgraph.PlotCurveItem(*args, **kargs)[source]#

Class representing a single plot curve. Instances of this class are created automatically as part of PlotDataItem; these rarely need to be instantiated directly.


  • Fast data update

  • Fill under curve

  • Mouse interaction



Emitted when the data being plotted has changed

sigClicked(self, ev)

Emitted when the curve is clicked

__init__(*args, **kargs)[source]#

Forwards all arguments to setData.

Some extra arguments are accepted as well:



The parent GraphicsObject (optional)


If True, the item will emit sigClicked when it is clicked on. Defaults to False.


Return a QPainterPath representing the clickable shape of the curve

setBrush(*args, **kargs)[source]#

Sets the brush used when filling the area under the curve. All arguments are passed to mkBrush.

setClickable(s, width=None)[source]#

Sets whether the item responds to mouse clicks.

The width argument specifies the width in pixels orthogonal to the curve that will respond to a mouse click.


Change the composition mode of the item. This is useful when overlaying multiple items.


mode (QtGui.QPainter.CompositionMode) –

Composition of the item, often used when overlaying items. Common options include:

QPainter.CompositionMode.CompositionMode_SourceOver (Default) Image replaces the background if it is opaque. Otherwise, it uses the alpha channel to blend the image with the background.

QPainter.CompositionMode.CompositionMode_Overlay Image color is mixed with the background color to reflect the lightness or darkness of the background

QPainter.CompositionMode.CompositionMode_Plus Both the alpha and color of the image and background pixels are added together.

QPainter.CompositionMode.CompositionMode_Plus The output is the image color multiplied by the background.

See QPainter::CompositionMode in the Qt Documentation for more options and details

setData(*args, **kargs)[source]#


x, y

(numpy arrays) Data to display


Pen to use when drawing. Any single argument accepted by mkPen is allowed.


Pen for drawing behind the primary pen. Usually this is used to emphasize the curve by providing a high-contrast border. Any single argument accepted by mkPen is allowed.


(float or None) Fill the area under the curve to the specified value.


(bool) If True, an outline surrounding the fillLevel area is drawn.


Brush to use when filling. Any single argument accepted by mkBrush is allowed.


(bool) Whether to use antialiasing when drawing. This is disabled by default because it decreases performance.


(str or None) If ‘center’, a step is drawn using the x values as boundaries and the given y values are associated to the mid-points between the boundaries of each step. This is commonly used when drawing histograms. Note that in this case, len(x) == len(y) + 1

If ‘left’ or ‘right’, the step is drawn assuming that the y value is associated to the left or right boundary, respectively. In this case len(x) == len(y) If not passed or an empty string or None is passed, the step mode is not enabled.


Argument specifying how vertexes should be connected by line segments.

‘all’ (default) indicates full connection.
‘pairs’ draws one separate line segment for each two points given.
‘finite’ omits segments attached to NaN or Inf values.
For any other connectivity, specify an array of boolean values.


See setCompositionMode.


(bool, defaults to False) Optimization flag that can speed up plotting by not checking and compensating for NaN values. If set to True, and NaN values exist, the data may not be displayed or the plot may take a significant performance hit.

If non-keyword arguments are used, they will be interpreted as setData(y) for a single argument and setData(x, y) for two arguments.

Notes on performance:

Line widths greater than 1 pixel affect the performance as discussed in the documentation of PlotDataItem.


Sets the level filled to when filling under the curve

setPen(*args, **kargs)[source]#

Set the pen used to draw the curve.


Sets the mode that decides whether or not lines are drawn as segmented lines. Drawing lines as segmented lines is more performant than the standard drawing method with continuous lines.


mode (str) –

'auto' (default) segmented lines are drawn if the pen’s width > 1, pen style is a solid line, the pen color is opaque and anti-aliasing is not enabled.

'on' lines are always drawn as segmented lines

'off' lines are never drawn as segmented lines, i.e. the drawing method with continuous lines is used

setShadowPen(*args, **kargs)[source]#

Set the shadow pen used to draw behind the primary pen. This pen must have a larger width than the primary pen to be visible. Arguments are passed to mkPen


When it is known that the plot data passed to PlotCurveItem contains only finite numerical values, the skipFiniteCheck property can help speed up plotting. If this flag is set and the data contains any non-finite values (such as NaN or Inf), unpredictable behavior will occur. The data might not be plotted, or there migth be significant performance impact.