Pandas function to take to the first value for each of a column value

pandas_first_by_column.py

def first_by_column(df, colname):
    """
    Pandas function to take to the first value for each of a column value.
    Useful if the table if sorted in descending order and you want to group over
    a particular column, to find the max for each value of that field.
    """
    newdf = []
    #print(colname)
    #print(df)
    colvals = pd.unique(df.loc[:, [colname]].squeeze())
    #print(colvals)
    for f in colvals:
        newdf.append(df.loc[df[colname] == f].iloc[0,:])
    return pd.concat(newdf, axis=1).T

Then graphs can be plotted using

w = max_by_column(df, 'colname')
w.apply(pd.to_numeric, errors='ignore').plot.line(y='mean corr', x='colname', logx=True)