如何使用python pandas向下一個單元格添加值

Question

我有一個我感興趣的表中的值“x”。我想首先找到值“x”在表中的位置，然后在“x”右側的單元格中添加一個字符串“s” （下一列但同一行）。

df[df.ix('x')] = s #would replace 'x' with 's'
df[df.ix('x')+1] = s #so i tried it with '+1' to indicate the same row but next the column but the syntax is wrong.

更新：

示例原始表數據 -

columnA    columnB
 A
 B
 X
 C
 X
 D

期望的結果 -

columnA       columnB
 A          
 X            S
 X            S
 B
 X            S
 C

我的簡化版本代碼：

    data = pd.read_excel('C:/Users/....table.xlsx', sep='\t')

    for vh in data["columnA"]:
            data[df.ix('X')+1] = s
    #obviously the '+1' syntax is wrong, how should i change it? 
    #i want S in columnB where there is X in column A

提前致謝！

更新新代碼：

   for line in f:
       for vh in data["columnA"]:
            vh = vh.rstrip()
            tmp = data[line in vh]
            tmp = tmp[list(tmp.columns[-1]) + tmp.columns.tolist()[:-1]]
            tmp.columns = data.columns
            data[tmp] = string

我認為語法是錯誤的，有人知道嗎？ 謝謝

Answer 1

假設您的 DataFrame 的最后一列中沒有'x'值：

tmp = df == 'X' # boolean mask
tmp = tmp[list(tmp.columns[-1]) + tmp.columns.tolist()[:-1]] # shift the order of columns to 1 ahead
tmp.columns = df.columns # restore names order in the mask
df[tmp] = 'S' # setting the s value to the cell right after the 'X'

對於您的兩列 DataFrame 就這么簡單：

df["columnB"] = df["columnA"].apply(lambda x: 'S' if x == 'X' else '')