Question: Let's say I want to visualize how my hypothetical students are doing with respect to their majors. I have 32 students in my class Data Frames 101. What I'm interested in doing is plotting the percent of students per major per grade decile.

Here's my sample data frame.

```
# Grade Decile
grade <- c(90, 90, 90, 80, 80, 80, 80, 70, 70, 60, 50, 50)
# Student Major
major <- c("history", "math", "science", "history", "science", "english", "math", "english", "math", "english", "math", "history")
# Number of students per major per decile
num <- c(3, 6, 2, 3, 5, 2, 4, 5, 5, 2, 1, 1)

df <- data.frame(grade, major, num)

```

Then I extract only the English majors.

```
df_english <- df[df$major == "english",]

```

How do I plot the **percentage** of English majors from the total number of majors of the students who scored a certain grade?

Ultimately what I'm trying to show (with this hypothetical data set) is how many students who scored a certain grade chose a certain major, but controlling for the unevenness in the number of students in a majors.

I tried plotting df\_english$num against df\_english$grade divided by nrow(df$grade), but I think I'm way off base here. I also tried adding a new column again using nrow(df$grade), but no dice.

Any advice, criticism, pseudo-code, direction, or actual code is welcome. Base R or something from the tidyverse is equally welcome.

Answer: 
It is also possible that your module is in development mode and you have the buggy sql query in sql/install.php or sql/uninstall.php in your module folder. This happened in my case.
Try [disable debug mode](https://www.prestashop.com/forums/topic/575132-how-to-enable-debug-mode-on-prestashop-17-and-older-versions-turn-on-error-reporting-blank-page/). It's working in my case:

```php
if (!defined('_PS_MODE_DEV_')) {
    define('_PS_MODE_DEV_', false);
}

```