# Threshold for removing correlated variables
threshold = 0.9

# Absolute value correlation matrix
corr_matrix = app.corr().abs()

# Upper triangle of correlations
upper = corr_matrix.where(np.triu(np.ones(corr_matrix.shape), k=1).astype(np.bool))

# Select columns with correlations above threshold
to_drop = [column for column in upper.columns if any(upper[column] > threshold)]

# Remove the columns
app = app.drop(columns = to_drop)