Welcome to the community!

First of all, why are the diagonals zero instead of being one?

Second, you can plot using `heatmap`

.

Example:

```
text_data <- "A B C
A 0.00 0.43 0.32
B 0.43 0.00 0.23
C 0.32 0.23 0.00"
correlation_matrix <- as.matrix(x = read.table(text = text_data,
header = TRUE))
# full plot
heatmap(x = correlation_matrix,
Rowv = NA,
Colv = NA,
distfun = NA,
hclustfun = NA,
symm = TRUE,
revC = TRUE,
scale = "none")
```

```
# lower triangular
lower_correlation_matrix = correlation_matrix
lower_correlation_matrix[upper.tri(x = lower_correlation_matrix)] = NA
heatmap(x = lower_correlation_matrix,
Rowv = NA,
Colv = NA,
distfun = NA,
hclustfun = NA,
symm = FALSE,
revC = TRUE,
scale = "none")
```

^{Created on 2021-03-22 by the reprex package (v1.0.0)}

Hope this helps.