熊猫ValueError:不能将字符串转换为浮点数:'p-'

So, I have a dataframe with more that 10^6 lines in it and I am just doing a simple conversion of lat (degrees min) to lat (degrees only). Yet there are lines in my frame which have a string "p-" which kills my loop early on. I have tried a few things (below).So, I have a dataframe with more that 10^6 line