Display actions

Expand
Entire
Rebin
User_Contour
Use of Marks
Highlight marked area
Project, Profile
ProjectF, Project along function
Project Both
Transpose
Rotate
Superimpose
Show in same range
Show statistics only
Magnify
RedefineAxis
Add new axis
Select Inside
Log scale

Use of marks

Marks are used when expanding and fitting histograms. They are set pressing the middle mouse button in a histogram. If no marks are active the lower and upper edges of the histogram are used, if only one mark is active the lower or upper edge is used as the second mark depending on the position of the InOutSide switch. Marks may be set using keyboard input. (Set2Marks). They can be converted to windows. These windows may be written to a workfile to be used by other programs like cuts in 2dim histograms.

Highlight marked area

Fill the area of a 1-dim histogram between 2 marks with a selectable color. The fillarea attributes of the generated TGraph may be changed afterwards invoking the SetFillAttributes popup menu with the right mouse. Saving the histogram to a file will also save this area.

Expand

Expand histogram using marks, if only one mark is active the lower edge is used as the second mark. This builds a new histogram, under- and overflow bins will be refilled correctly. Possible active cuts will be applied. The command Entire shows the full range range again. Cuts are ignored. To get only an expanded view move the mouse into the labels of the wanted axis, the cursor should turn into a hand with a forefinger, press the left mouse button and drag the mouse to the required position an release the button. To get back to the full picture use the command Entire from the Display popup menu.

Show entire histogram

Show full range of histogram

RedefineAxis

The values of the axis labels may be redefined by providing new lower and upper limits for the axis. In this way the picture can reflect a calibrated spectrum. Note: This only changes the appearance of the picture. The histogram itself remains unchanged. For calibration using a non linear function consult this.

ProjectX,Y ProfileX,Y

The commands ProjectX, ProjectY, ProfileX produce projections resp. profiles on the X or Y axis for a 2-dim histogram. Active cuts will be applied.

Project along function

ProjectF will project the difference of the Y - values to the values of a function previously generated by a fit (See Help on Fitting). The result is the superposition of slices in X of the 2-dim histogram where each slice is shifted such that its Y - value equal to the function value is moved to zero. So the resulting projection on the Y-axis will be centered at zero. This allows a banana shaped distribution to be straightened so the banana shows its real thickness in the Y-projection.

Project on X and Y

The command ProjectBoth produces projections on the X and Y axis for a 2-dim histogram in the same picture. The attached figure demonstrates this.

The ratio of the space taken by the scatter plot and the projections may by adjusted by the parameter Project_Both_Ratio (see Help_on_Default_Window_Sizes

Transpose a 2-dim histogram

Exchange X and Y-axis of 2-dim histogram. This is useful together with ProjectF

Rotate a 2-dim histogram

Rotate a 2-dim histogram. This is normally done to align structures along the X or Y-axis before project or slice operations.

The determine the rotation angle a pol1 (straight line) fit to user defined marks should be done before. Alternativly the angle may be directly given in degrees. Note: This is normally only useful if X and Y-axis have the same scale. The absolute values of the scales are no longer meaningful.

Show in same range

Show a histogram in same range as this one. If no histogram is selected a list of histograms in memory is presented allowing a selection.

Show statistics only

This prints contents, mean, sigma applying active cuts.

Superimpose

Superimpose a histogram on existing picture. A histogram can be selected from a histogram list by pressing the grey button left of the name. If none is selected a list of histograms in memory is presented from which selection can be done. The latter is needed to show histograms which result from an operation (scaled, summed etc.). histogram. For 1-dim the color code is taken from its position + 2 (position 1 gets red etc.) With this command the same scale is used as for the original histogram. A command Superimpose scaled is provided for 1-dim hists to scale the superimposed histogram to the maximum of the original one in the displayed region.

Magnify

This operation is useful for histograms with many bins. The (virtual) canvas is extended in such a way that one bin spans at least 2 pixels on screen. A scrollbar is added to allow scrolling through the entire picture.

Add new X-Y axis

This allows to add an extra X or Y axis at top or on the right side of a histogram. The axis range may be choosen different from the original one.

Select Inside

This option determines if points inside or outside are choosen when applying cuts.

Log Y, Z scale

This option is added for convenience to choose logarithmic Y or Z-scale. The same can be achievced from a canvas popup menu (Right mouse in a canvas outside the borders of a histogram).

Rebin

Rebin this histogram using the ROOT builtin command. This command uses the sum of the bin contents. There is an extended Rebin command provided by HistPresent which produces a new histogram with sum or avarage of the bin contents selectable.

User defined contours

Levels and colors in 2-dim histograms using the drawing options colz or similiar are normally automatically adjusted using 20 equidistant levels and a color spectrum blue-green-yellow-red (rainbow colors). Levels and colors can be selected using Set User Contours in the Display popup menu. Color numbers or levels may all be set to 0, in this case the default colors (e.g. rainbow) and the default equidistant levels are used. The convention is such that cells with content greater than a level value and less or equal to the following value get the corresponding color. That means cells with content below the lowest level are in background color (not visible). So in the normal case when no cells with negative content are present the lowest level should be 0. These settings can be saved to a rootfile and reused later. Save is done be the command Save User Contours Restore is done by selecting the required contour object in the File list and pressing Use Selected Contours Clear User Contours establishes the default 20 equidistant levels again. This feature is especially useful to get nice logarithmic contour levels. E.g.: Just define contour levels 1, 10, 100, 1000, choose log Z-scale and set LogScale_Minumum to 0 if the bincontents are integer numbers. Note: With user contours the picture itself will not change when switching lin - log, only the color palette (Z-scale) will change.