创建一个在两个数据框之间具有匹配和不匹配的数据框

Question

I am trying to create a heatmap in order to visualize matches and mismatches between some predicted and expected values.

If a is the data frame containing the predicted values and b the expected ones;

a = rbind (sample(0:1, size=14, replace = T),sample(0:1, size=14, replace = T))
b = rbind (sample(0:1, size=40, replace = T),sample(0:1, size=40, replace = T))

How can I create a third data frame containing only the common columns of a & b and give back

• a certain value when a value is the same in the two data frames
• another value if the predicted value was 0 and the expected 1
• another value if the predicted value was 1 and the expected 0.

Answer 1

## your example data are matrices, 
## let's make them data frames:
a = as.data.frame(a)
b = as.data.frame(b)

common_cols = intersect(names(a), names(b))

## see where they are equal
## TRUE means equal, FALSE means not equal
a[common_cols] == b[common_cols]
#         V1   V2    V3   V4    V5    V6   V7    V8    V9   V10   V11   V12   V13  V14
# [1,]  TRUE TRUE FALSE TRUE FALSE FALSE TRUE FALSE  TRUE FALSE FALSE  TRUE FALSE TRUE
# [2,] FALSE TRUE  TRUE TRUE  TRUE FALSE TRUE  TRUE FALSE  TRUE FALSE FALSE  TRUE TRUE

## see the difference
## 0 means a and b are equal
## 1 means a is 1 and b is 0
## -1 means a is 0 and b is 1
a[common_cols] - b[common_cols]
#   V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12 V13 V14
# 1  0  0 -1  0  1 -1  0  1  0  -1   1   0  -1   0
# 2  1  0  0  0  0  1  0  0 -1   0  -1  -1   0   0