An Python version of an R ifelse statement

I am trying to learn Python after learning R and an simple ifelse statement.

In R I have:

df$X <- if(df$A == "-1"){-df$X}else{df$X}

But I am unsure how to implement it in Python, I have tried:

df['X'][df['A'] <1] = -[df['X']
df['X'][df['A'] >1] = [df['X']

But this leads to errors, would appreciate some help.