我想通过使用for循环替换R中的缺失值。 所以，我做了循环。数据框＆＃34; hflights_df＆＃34;有227496行和21列。
hflights_df=tbl_df(hflights)
for (i in 1:21){
for(j in 1:227496){
ifelse(is.na(hflights_df[j,i]),0,hflights_df[j,i])
}}
在此之后，我通过usign summary函数检查了缺失值是否消失。但是，仍然缺少数据。
summary(hflights_df)
Year Month DayofMonth DayOfWeek DepTime ArrTime UniqueCarrier
Min. :2011 Min. : 1.000 Min. : 1.00 Min. :1.000 Min. : 1 Min. : 1 Length:227496
1st Qu.:2011 1st Qu.: 4.000 1st Qu.: 8.00 1st Qu.:2.000 1st Qu.:1021 1st Qu.:1215 Class :character
Median :2011 Median : 7.000 Median :16.00 Median :4.000 Median :1416 Median :1617 Mode :character
Mean :2011 Mean : 6.514 Mean :15.74 Mean :3.948 Mean :1396 Mean :1578
3rd Qu.:2011 3rd Qu.: 9.000 3rd Qu.:23.00 3rd Qu.:6.000 3rd Qu.:1801 3rd Qu.:1953
Max. :2011 Max. :12.000 Max. :31.00 Max. :7.000 Max. :2400 Max. :2400
NA's :2905 NA's :3066
FlightNum TailNum ActualElapsedTime AirTime ArrDelay DepDelay
Min. : 1 Length:227496 Min. : 34.0 Min. : 11.0 Min. :-70.000 Min. :-33.000
1st Qu.: 855 Class :character 1st Qu.: 77.0 1st Qu.: 58.0 1st Qu.: -8.000 1st Qu.: -3.000
Median :1696 Mode :character Median :128.0 Median :107.0 Median : 0.000 Median : 0.000
Mean :1962 Mean :129.3 Mean :108.1 Mean : 7.094 Mean : 9.445
3rd Qu.:2755 3rd Qu.:165.0 3rd Qu.:141.0 3rd Qu.: 11.000 3rd Qu.: 9.000
Max. :7290 Max. :575.0 Max. :549.0 Max. :978.000 Max. :981.000
NA's :3622 NA's :3622 NA's :3622 NA's :2905
Origin Dest Distance TaxiIn TaxiOut Cancelled
Length:227496 Length:227496 Min. : 79.0 Min. : 1.000 Min. : 1.00 Min. :0.00000
Class :character Class :character 1st Qu.: 376.0 1st Qu.: 4.000 1st Qu.: 10.00 1st Qu.:0.00000
Mode :character Mode :character Median : 809.0 Median : 5.000 Median : 14.00 Median :0.00000
Mean : 787.8 Mean : 6.099 Mean : 15.09 Mean :0.01307
3rd Qu.:1042.0 3rd Qu.: 7.000 3rd Qu.: 18.00 3rd Qu.:0.00000
Max. :3904.0 Max. :165.000 Max. :163.00 Max. :1.00000
NA's :3066 NA's :2947
CancellationCode Diverted
Length:227496 Min. :0.000000
Class :character 1st Qu.:0.000000
Mode :character Median :0.000000
Mean :0.002853
3rd Qu.:0.000000
Max. :1.000000
如何将缺失值替换为0？