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Editorial Team
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Asked: 2026-05-31T20:50:22+00:00

I have a dataframe that looks like this: person n start end 1 sam

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I have a dataframe that looks like this:

       person n start end
1         sam 6     0   6
2        greg 5     6  11
3     teacher 4    11  15
4         sam 4    15  19
5        greg 5    19  24
6       sally 5    24  29
7        greg 4    29  33
8         sam 3    33  36
9       sally 5    36  41
10 researcher 6    41  47
11       greg 6    47  53

Where start and end are times or durations (sam spoke from 0 to 6; greg from 6 to 11 etc.). n is how long (in this case # of words) the person spoke. I want to plot this as a time line in base R (I eventually may ask a similar question using ggplot2 but this answer is specific to base R [when I say base I mean the packages that come with a standard install]).

The y axis will be by person and the x axis will be time. Hopefully the final product looks something like this for the data above:

Timeline_Graph

I would like to use base R to make this. I’m not sure how to approach this. My thoughts are to use a dot plot and plot a dotplot but leave out the dots. Then go over this with square end segments. I’m not sure about how this will work since the segments need numeric x and y points to make the segments and the y axis is categorical. Another thought is to convert the factors to numeric (assign each factor a number) and plot as a blank scatterplot and then go over with square end line segments. This could be a powerful tool in my field looking at speech patterns.

I thank you in advance for your help.

PS the argument for square ended line segments is segments(... , lend=2) to save time looking this information up for those not familiar with all the segment arguments.

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1 Answer

  1. Editorial Team

    While the y-axis is categorical all you need to do is assign numbers to the categories (1:5) and track them. Using the default as.numeric() of the factor will usually number them alphabetically but you should check anyway. Make your plot with the xaxt = ‘n’ argument. Then use the axis() command to put in a y-axis.

    axis(2, 1:5, myLabels)

    Keep in mind that whenever you’re plotting the only way to place things is with a number. Categorical x or y values are always just the numbers 1:nCategories with category name labels in place of the numbers on the axis.

    Something like the following gets you close enough (assuming your data.frame object is called datf)…

    datf$pNum <- as.numeric(datf$person)
plot(datf$pNum, xlim = c(0, 53), type = 'n', yaxt = 'n', xlab ='Duration (words)', ylab = 'person', main = 'Speech Duration')
axis(2, 1:5, sort(unique(datf$person)), las = 2, cex.axis = 0.75)
with(datf, segments(start, pNum, end, pNum, lwd = 3, lend=2))
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