ggplot2 line chart gives geom path Each group consist of only one observation Do you need to adjust the group aesthetic

Question

With this data frame   df     year pollution 1 1999 346 82000 2 2002 134 30882 3 2005 130 43038 4 2008  88 27546   I try to create a line chart like this     plot5  lt - ggplot df  aes year  pollution                geom point                geom line                labs x    Year   y    Particulate matter emissions  tons    title    Motor vehicle emissions in Baltimore     The error I get is      geom path  Each group consist of only one observation  Do you need to   adjust the group aesthetic    The chart appears as a scatter plot even though I want a line chart  I tried to replace geom line   with geom line aes group   year   but that didn t work    In an answer I was told to convert year to a factor variable  I did and the problem persists  This is the output of str df  and dput df     data frame     4 obs  of  2 variables     year       num  1 2 3 4    pollution  num  1 4 1d   346 8 134 3 130 4 88 3     - attr     dimnames   List of 1            chr   1999   2002   2005   2008   structure list year   c 1  2  3  4   pollution   structure c 346 82   134 308821199349  130 430379885892  88 275457392443    Dim   4L   Dimnames   list      c  1999    2002    2005    2008        Names   c  year     pollution    row names   c NA  -4L   class    data frame

User · Answer

You get this error because one of your variables is actually a factor variable . Execute

str(df)

to check this. Then do this double variable change to keep the year numbers instead of transforming into "1,2,3,4" level numbers:

df$year <- as.numeric(as.character(df$year))

EDIT: it appears that your data.frame has a variable of class "array" which might cause the pb. Try then:

df <- data.frame(apply(df, 2, unclass))

and plot again?

User · Answer

I got a similar prompt  It was because I had specified the x-axis in terms of some percentage  for example  10 A  20 B        So an alternate approach could be that you multiply these values and write them in the simplest form

User · Answer

You only have to add group   1 into the ggplot or geom line aes        For line graphs  the data points must be grouped so that it knows which points to connect  In this case  it is simple -- all points should be connected  so group 1  When more variables are used and multiple lines are drawn  the grouping for lines is usually done by variable    Reference  Cookbook for R  Chapter  Graphs Bar and line graphs  ggplot2   Line graphs   Try this   plot5  lt - ggplot df  aes year  pollution  group   1              geom point              geom line              labs x    Year   y    Particulate matter emissions  tons                   title    Motor vehicle emissions in Baltimore

User · Answer

I found this can also occur if the most of the data plotted is outside of the axis limits  In that case  adjust the axis scales accordingly

User · Answer

Start up R in a fresh session and paste this in   library ggplot2   df  lt - structure list year   c 1  2  3  4   pollution   structure c 346 82   134 308821199349  130 430379885892  88 275457392443    Dim   4L   Dimnames   list      c  1999    2002    2005    2008        Names   c  year     pollution    row names   c NA  -4L   class    data frame    df    lt - lapply df  as numeric    make all columns numeric  ggplot df  aes year  pollution                geom point                geom line                labs x    Year                    y    Particulate matter emissions  tons                     title    Motor vehicle emissions in Baltimore

User · Answer

I had similar problem with the data frame   group time weight loss 1 Control  wl1    4 500000 2    Diet  wl1    5 333333 3  DietEx  wl1    6 200000 4 Control  wl2    3 333333 5    Diet  wl2    3 916667 6  DietEx  wl2    6 100000 7 Control  wl3    2 083333 8    Diet  wl3    2 250000 9  DietEx  wl3    2 200000   I think the variable for x axis should be numeric  so that geom line knows how to connect the points to draw the line   after I change the 2nd column to numeric    group time weight loss 1 Control    1    4 500000 2    Diet    1    5 333333 3  DietEx    1    6 200000 4 Control    2    3 333333 5    Diet    2    3 916667 6  DietEx    2    6 100000 7 Control    3    2 083333 8    Diet    3    2 250000 9  DietEx    3    2 200000   then it works

[r] ggplot2 line chart gives "geom_path: Each group consist of only one observation. Do you need to adjust the group aesthetic?"

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