R - Count numbers of certain values in each column

Question

I have found similar questions to mine, but none of them explains how to do that for each column of a dataframe.

I have a dataframe like this:

x1 = seq(12, 200, length=20)
x2 = seq(50, 120, length=20)
x3 = seq(40, 250, length=20)
x4 = seq(100,130, length=20)
x5 = seq(10, 300, length=20) 

df = data.frame(V1=x1, V2=x2, V3=x3, V4=x4, V5=x5) 

Now I want to get the number of values that are greater than 120 for each column.

I have tried:

nrow(df[,1] >120)

That didnt work, it says 0, but its not true, and also I want to do all columns automatically.

Answer 1

You can use tidyverse to solve this.

library(tidyverse)

df%>%
gather(x, value, V1:V5)%>%
group_by(x)%>%
tally(value > 120)

# A tibble: 5 x 2
  x         n
  <chr> <int>
1 V1        9
2 V2        0
3 V3       12
4 V4        7
5 V5       12

Hope this helps.