How to combine several dataframes with different rows using R?

Question

I have several text files containing 2 columns and different row numbers. I would like to follow drawing a plot using ggplot2 as explained enter link description here; however, it works well for dataframes with equal row numbers, and I couldn't reproduce it with dataframes with different row numbers. please let me know how I should combine these data frames (dataframes with different row number) using R?

case siza
case1 129
case2 129
case3 130 
case4 131
case5 132
case6 132

Thank you

I assume they're the same columns in each data frame, named the same? If so, just use z <- rbind(x, y) where x and y are your two data frames. — giraffehere
– giraffehere, Commented Jan 8, 2016 at 21:28
dataframe have the same columns but, the different row. For right plotting, they have to combined based on 2th coulmns (named for example "size"), could you please help me how I can do it for these dataframes? I used "df = data.frame(df1$size,df2$size) for dataframes with equal row number, but don't know for dataframes with different row number. — Mary
– Mary, Commented Jan 8, 2016 at 21:59
are you trying to (1) merge/bind the columns together, then (2) melt and plot them? If so you'll want to cbind the columns then plot them. — desc
– desc, Commented Jan 9, 2016 at 1:07
If you edit your question with some sample data, you will get a clearer answer. — alistaire
– alistaire, Commented Jan 9, 2016 at 2:49
Yes, I used df = data.frame(df1$size,df2$size), then melt and finally plotting for dataframes with the equal row number, but I have a problem with combining dataframes with different row numbers. — Mary
– Mary, Commented Jan 9, 2016 at 8:13

desc · Accepted Answer · 2016-01-12 23:54:53Z

1

It seems from the comments that you're actually trying to merge multiple columns and then plot each column individually. The problem, however, is that each of these columns has a different number of rows. Therefore you need to combine them based on some common variable (i.e. row names).

Using the examples from the link you provided:

df1 = data.frame(size=runif(300,300,1200))

#now adding an unequal column
df2 = data.frame(size=df1[c(1:275),])

Now merge the data frames based on row number. "all=TRUE" keeps all the values, "by=0" merges by row.names.

df.all=merge(df1$size,df2$size,by=0,all=TRUE)

#and to order the row names.
df.all=df.all[order(as.numeric(df.all[,1])),]

#finally if you want to remove the NA values
df.all[is.na(df.all)]=0

Does that get you the data.frame you want?

edited Jan 12, 2016 at 23:54

answered Jan 12, 2016 at 19:55

desc

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