使用r和ggplot绘制图形时如何将数据框映射为x轴？

Question

I have such a data frame df1 , to indicate the emotion status of a certain user in a time series:

0.00
0.10
0.20
0.00
0.70 
....

And another data frame df2 , to indicate the number of record in df1 in a certain day:

2015-01-02   1
2015-01-03   2
2015-01-04   3

ie, the first value belongs to 01-02 , the second and the third value belongs to 01-03 and so on.

Now I'd like the plot a point graph with date as x-axis and emotional value as y-axis. How can I do that? Furthermore, How to skip all the 0.0 value and just show the value other than zero? Thanks!

Answer 1

There are two separate steps in the solution I propose. First create a vector dates with the sequence of dates used, secondly use dplyr::filter to remove the zero values.

For the first step you can use a combination of lapply and rep as follows:

dates <- c(lapply(seq(nrow(df2)), function(idx) rep(df2$date[idx], df2$count[idx])), recursive = TRUE)

the c(..., recursive = TRUE) is around it to convert the result to a flat vector.

Then combine into a data.frame filter and plot as follows:

df3 <- cbind(df1, data.frame(dates = as.POSIXct(dates)))
ggplot(df3 %>% filter(state != 0.0), aes(x=dates, y = state)) + geom_point()