Assignments: numerics, strings and .loc · Issue #6171 · pandas-dev/pandas (original) (raw)

Why would assigning an entire column to an array of values work differently with numbers vs strings?

Assigning numeric values:

df = pd.DataFrame(columns=['x', 'y']) df['x'] = [1, 2] df x y 0 1 NaN 1 2 NaN

Assigning string values:

df = pd.DataFrame(columns=['x', 'y']) df['x'] = ['1', '2'] ValueError: could not broadcast input array from shape (2) into shape (0)

Btw according to latest docs .loc can append, but can it append more than one value at once?

Setting multiple via .loc:

df = pd.DataFrame(columns=['x', 'y']) df.loc[:, 'x'] = [1, 2] df Empty DataFrame Columns: [x, y] Index: [] df.loc[[0, 1], 'x'] = [1, 2] df Empty DataFrame Columns: [x, y] Index: [] df.loc[0:2, 'x'] = [1, 2] df Empty DataFrame Columns: [x, y] Index: []

Setting single via .loc: (this works ofc)

df = pd.DataFrame(columns=['x', 'y']) df.loc[0, 'x'] = 1 df x y 0 1 NaN