Question

这是我最初的df

       China  USA
2009    NaN   -9
2010    1.2    8
2011    1.5  NaN
2014    5.0  NaN
2015    NaN    8

然后我使用reindex方法添加一些索引

frame2=frame1.reindex([2009,2010,2011,2012,2013,2014,2015,2016],method="ffill")

我希望第2帧通过

       China  USA
2009    NaN   -9
2010    1.2    8
2011    1.5  NaN
2012    NaN  NaN
2013    NaN  NaN
2014    5.0  NaN
2015    NaN    8
2016    NaN  NaN

到

       China  USA
2009    NaN   -9
2010    1.2    8
2011    1.5    8
2012    1.5    8
2013    1.5    8
2014    5.0    8
2015    5.0    8
2016    5.0    8

但它返回了

       China  USA
2009    NaN   -9
2010    1.2    8
2011    1.5  NaN
2012    1.5  NaN
2013    1.5  NaN
2014    5.0  NaN
2015    NaN    8
2016    NaN    8

它仅填充了我df的某些条目。

Answer 1

从某种意义上说，它确实进行了前期填充。它从import numpy as np import re waters = np.full((10,10), '##','U2') headers = ['A','B','C','D','E','F','G','H','I','J'] #PRINTS THE BOARD def printBoard(): for i,header in enumerate(headers): if i == 0: print(' ',end='') print(header + ' ',end='') if i == len(headers)-1: print() for x,line in enumerate(waters): print('%2d'%(x),end='') [print(' '+pos,end='') for pos in line] print() printBoard() board_x_coord = { "A":0, "B":1, "C":2, "D":3, "E":4, "F":5, "G":6, "H":7, "I":8, "J":9 } ship_type = [ ["CV","Carrier",5], ["BB","Battleship",4], ["CA","Cruiser",3], ["SS","Submarine",3], ["DD","Destroyer",2], ] def board_coord_to_npcoord(ship,coord): try: result = re.findall(r'([A-J])(\d)([A-J])(\d)',coord)[0] x_crd_a = board_x_coord.get(result[0]) y_crd_a = int(result[1]) x_crd_b = board_x_coord.get(result[2]) y_crd_b = int(result[3]) vertical = ship[2] == abs(x_crd_b - x_crd_a + 1) and y_crd_a == y_crd_b horizontal = ship[2] == abs(y_crd_b - y_crd_a + 1) and x_crd_a == x_crd_b valid = vertical or horizontal if valid == False: print('Invalid length') return False if vertical: waters[y_crd_a][x_crd_a:x_crd_b + 1] = ship[0] print(waters[y_crd_a][x_crd_a:x_crd_b]) printBoard() print('X: %s , Y: %s , X: %s , Y: %s' %(x_crd_a,y_crd_a,x_crd_b,y_crd_b)) return True except ValueError: print('Error. Try again.') return False for ship in ship_type: while True: print('Coordinates for %s (%s): ' %(ship[1],ship[2]),end='') if board_coord_to_npcoord(ship,input()): break的{{1}}到NaN的{{1}}以及2015的{{1}}到2016提出了<。 / p>

相反，请在China之后执行2011

进一步的解释

USA

您的方法执行了应有的操作。如果采用在现有索引中找到的值并将其传播给所有新索引。

ffill

python pandas方法“填充”

1 个答案:

进一步的解释